Fiber Optic Tensioning Reel Sub-System In Robotic Fiber Optic Cross-Connect Systems, Sub-Systems, Devices And Methods

ABSTRACT

A tensioning spool apparatus for storage of optical fiber exhibiting reduced variation of tension during a retraction cycle versus an extension cycle of fiber over a predefined range of spool rotation cycles, the optical fiber dynamically extended under tension from the spool.

REFERENCE TO RELATED APPLICATIONS

This patent claims the benefit of U.S. Provisional Patent Application62/924,291, filed Oct. 22, 2019, U.S. Provisional Patent Application62/898,353, filed Sep. 10, 2019, U.S. Provisional Patent Application62/897,168, filed Sep. 6, 2019, and U.S. Provisional Patent Application62/896,050, filed Sep. 5, 2019, and U.S. Provisional Patent Application63/073,842, filed Sep. 2, 2020, the entire contents of each of which arehereby fully incorporated herein by reference for all purposes.

COPYRIGHT STATEMENT

This patent document contains material subject to copyright protection.The copyright owner has no objection to the reproduction of this patentdocument or any related materials in the files of the United StatesPatent and Trademark Office, but otherwise reserves all copyrightswhatsoever.

FIELD OF THE INVENTION

This invention relates to systems, sub-systems, devices and methods toreconfigure a multiplicity of fiber optic cables within large scalerobotic cross-connect systems providing low loss, software-defined fiberoptic connections between a large number of pairs of ports. Moreparticularly, this invention relates to elements of such cross-connectsystems, including a high-reliability gripper for an actuated fiberoptic connector system, a high performance, narrow form factor,telescopic robotic arm for an actuated fiber optic connector system, afiber end face cleaning module having actuated, consistent fabric feed,and high-performance fiber optic tensioning reel elements and rollerassemblies to manage excess lengths of fiber optic cables therein.

BACKGROUND

Large scale automated fiber optic cross-connect switches andsoftware-defined patch-panels enable data centers and data networks withfiber optic interconnect fabrics to be fully automated, wherein thephysical network topologies are software-defined or programmable, forimproved efficiencies and cost savings.

Advances in the mathematics of topology and Knot and Braid Theory (U.S.Pat. Nos. 8,068,715, 8,463,091, 8,488,938, 8,805,155, 9,411,308; and10,042,122 to Kewitsch—hereinafter the “Kewitsch KBS Patents”) havesolved the fiber entanglement challenge for dense collections ofinterconnect strands undergoing arbitrary and unlimitedreconfigurations. Since this Knots, Braids and Strands (KBS) technologyscales linearly in the number of interconnect strands, significantbenefits over cross-bar switches (such as density and hardwaresimplicity) are realized. An exemplary high-reliability robotcross-connect system is described in Telescent's U.S. Pat. No.10,345,526, the entire contents of which are hereby fully incorporatedherein by reference for all purposes.

Systems featuring autonomous patch panel systems and implementing KBSalgorithms in accordance, e.g., with the Kewitsch KBS Patents referencedabove typically utilize a pick and place robotic actuation system with agripper at the end of the robotic arm to grab, transport and clean afiber optic connector and the self-tensioned, retractable fiber opticstrand extending from a central backbone in the system. The robotic armis of a narrow width and extended depth to allow it to descend into thedense fiber optic interconnect volume with no mechanical interferenceand no contact with surrounding fibers, yet still having sufficientrigidity to experience minimal deflection under transverse forcesincluding magnetic repulsion and tension originating from the fiberbeing carried in the gripper therein.

As described in U.S. Pat. No. 10,345,526, a gripper at the end of arobot arm is able to unplug any fiber connector from among an array offiber connectors inserted along connector rows, then transport it in adeterministic, optimal weaving pattern between the surrounding fiberconnectors of the array upon manipulation by a robot arm assembly.

Physical contact connectors, by virtue of the optical contact betweenradiused ferrule end faces and wear on the connector and adapterhousings, can begin to degrade after 1,000s of mating cycles. Thedurability can be substantially increased by, among other things,providing automatic fiber end-face cleaning capabilities. As described,e.g., in U.S. Pat. No. 8,068,715, the polished fiber end face of aconnector may be cleaned prior to insertion by use of an integratedfiber end face cleaning module comprising a fiber cleaning fabric ribbonin spooled form and a drive unit which automatically moves the fabricrelative to the fiber end face, thereby cleaning the fiber end faces ina non-wearing fashion.

In a particular embodiment, the fiber end-face of connectors may beautomatically processed by the cleaning module during a latter phase inits movement to a destination port. This ensures repeated low-loss fiberoptic connections free of contaminants on the delicate end face. Thecleaning system may use consumable cleaning fabric on spools,pressurized air, ultrasound, and/or wet chemical means.

The fiber optic connector is mechanically and removably latched withinthe gripper which is rigidly attached to a telescoping robot arm or thelike to position optical fiber connections. The cleaning module may bepositioned adjacent the robot arm, just beneath the robot mountingplatform near the top-most travel limit of the robot arm so that the armcan translate the end face of the optical fiber connector across and incontact with the cleaning fabric.

In an embodiment shown in U.S. Pat. No. 8,068,715, cleaning fabric isprovided in a spooled strip form and retained on spool cartridges withina slide-in tray module located below the bottom-most row of the inputterminal array. Dispensing of unused cleaning tape may be controlled bymotor(s). The cleaning module may eject used cleaning cartridges andinsert replacement tape. Cleaning of a connector may be achieved bycontacting a fiber's end face to the tape (e.g., supported byelastomeric backing) and by relative movement of the end face relativeto the tape.

Moreover, the excess lengths of the fiber optical cables moveable by therobot and gripper within the automated cross-connect system areautomatically retained by an arrangement of spools for fiber retentionand guides on a common substrate. While the tensioning spools/reelsdescribed in the Kewitsch patents operate as required, improvements aredesired including those relating to improvements in compactness,hardware simplicity and operative reliability, singly or in combination.

Retraction of any particular flexible circuit may be accomplished by aninternal power spring within each spool, which transfers torque to atake-up spool and maintains a required tension on the fiber opticcircuit. In an alternate embodiment, rotation of the take-up spool maybe achieved by a motorized means using a shared retraction motor driveunit and clutch mechanism to transfer a torque to each spool. Suchtensioning reduces slack cable within the interconnect volume. In afurther example, the automated cross-connect system uses an arrangementof spaced apart pulleys to retain a variable amount of optical fiber,separated into a set of fixed pulleys and a set of moveable springloaded pulleys, with a variable length of optical fiber cable woundtherebetween and with a tension that is a fraction of the spring force.This arrangement of pulleys enables a variable length of fiber to bestored and tensioned therein.

SUMMARY

The present invention is specified in the claims as well as in the belowdescription. Preferred embodiments are particularly specified in thedependent claims and the description of various embodiments.Cross-connect systems are comprised of gripper, robot, cleaningcartridge and fiber tensioning and storage sub-systems as disclosedherein.

Gripper Sub-System

One general aspect includes in a fiber optic cross-connect in which agripper selectively transports fiber optic connectors between differentpositions. The gripper also includes a stepper motor drive, responsiveto command signals and mounted on a support structure. The gripper alsoincludes a dual drum connected to the stepper motor drive and rotatableabout a first axis, said dual drum may include a top drum portion and abottom drum portion. The gripper also includes a plurality of bearingshafts slidably engaged in spaced apart relation in the supportstructure along axes perpendicular to the first axis. The gripper alsoincludes a pair of spaced apart terminal blocks fixedly mounted onopposite ends of the bearing shafts. The gripper also includes a lengthof drive string connected to the dual drum. The gripper also includeswhere a first portion of said drive string is positioned to wind aboutthe bottom drum portion when the drum is rotated in first direction, andwhere an end of said first portion of said drive string is connected toa first of said terminal blocks. The gripper also includes where asecond portion of said drive string is positioned to unwind about thetop drum portion when the drum is rotated in a first direction, andwhere an end of said second portion of said drive string is connected toa spring attached to a second of said terminal blocks. The gripper alsoincludes where rotation of the drum in said first direction causes thepair of spaced apart terminal blocks to move together.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   The gripper assembly where the drive string has a diameter of        about 0.73 mm.    -   The gripper assembly where the drive string may include a        multifilament yarn spun liquid crystal polymer.    -   The gripper assembly where the drive string is braided.    -   The gripper assembly where the drive string has at least 57 kg        (125-pound) tensile strength.    -   The gripper assembly where the drum has rounded flanges.    -   The gripper assembly where the spring enables about 6 mm of        compression.    -   The gripper assembly where the drum has a mandrel and where the        drive string passes through a hole in the mandrel to go from the        top drum portion to the bottom drum portion.    -   The gripper assembly where a portion of the drive string is        bonded to the mandrel.

Another general aspect includes an electrically actuated fiber opticconnector gripper device that attaches to a robot arm and generatesinsertion forces sufficient to transfer a first connector with a firstferrule in or out of a union coupler receptacle with potentially anopposing connector with a ferrule. The electrically actuated fiber opticconnector gripper device also includes a central member attachable tothe robot arm. The device also includes a stepper motor affixed tocentral member. The device also includes a gearbox with a rotatableshaft coupled to the stepper motor. The device also includes atwo-section drum, with a clockwise spool section and an adjacentcounterclockwise spool section, having a common rotation axis coupled tothe shaft of the gearbox. The device also includes a string attached tothe drum and wound in opposite sense onto the clockwise spool sectionand the counterclockwise spool section. The device also includes wherethe string exits the spool sections in substantially anti-paralleldirections perpendicular to rotation access of spool, the string affixedat a first end to a flexible spring member and affixed at a second endto a fixed clamp, where the first end and the second end are part of aconnector carrier that slides relative to central member and retains thefirst connector, where the connector carrier moves in a first directionwhen a length of string winds onto the clockwise spool section, and asubstantially identical length of string simultaneously unwinds from thecounterclockwise spool section, and moves in the opposite direction whenthe length of string unwinds from the clockwise spool and asubstantially identical length of string simultaneously winds onto thecounterclockwise spool.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   The device where the gripper device generates insertion forces        greater than 5 N.    -   The string may include a high strength, small diameter, flexible        string.    -   The device in which the central member and the connector carrier        are substantially planar, rigid, and parallel to one another.    -   Electrical signals that pass between the central member and the        carrier are transferred through a flexible multi-conductor        element.    -   The carrier includes a solenoid constructed and adapted to lock        the first connector into the carrier and to unlock the first        connector from the carrier when electrically energized.

Another general aspect includes a gripper device with first and secondtranslating members for plugging and unplugging spring-loaded ferrulesof fiber optic connectors from mating connector receptacles that requirea torque impulse when plugging and unplugging the connectors. Thegripper device also includes an actuator attached to first member. Thedevice also includes a rotating shaft exiting the actuator. The devicealso includes a gearbox with a gearbox shaft attached to the shaft, thegearbox increasing the torque output by the actuator. The device alsoincludes a double drum for winding and unwinding a flexible, low stretchdrive string under low static tension. The device also includes thedrive string is connected to a compliant element, and where the torqueimpulse imposed on gearbox when translating a second member is reducedby the compliant spring.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   The device where the first and second translating members        translate substantially parallel to one another and are        connected with a pair of spaced apart linear bearings.    -   The second member includes one or more pulleys around which the        drive string is wrapped.    -   The opposite ends of drive string are attached to the first        member.    -   The opposite ends of drive string are attached to the second        member and the compliant element is a spring.

Another general aspect includes an electro-mechanical interface for afiber connector gripper at the end of a robot arm. Theelectro-mechanical interface also includes an electrical connection forpower, motor and sensor lines between the robot arm and the gripper,between a pair of opposing gripper and arm circuit board assemblies,including an array of pins on gripper circuit board and pin receptacleson arm circuit board. The electro-mechanical interface also includes amechanical connection in which the gripper has a pair of guidereceptacles and the robot arm has a pair of posts, where the pair ofguide receptacles are plugged onto the pair of posts, and where theposts and receptacles are locked into one another with spring loadeddetent that engages a pocket on wall of posts. The electro-mechanicalinterface also includes an actuable locking clip to retain detent intodepression and maintain a rigid connection between gripper and robotarm, even during motion and vibration.

Another general aspect includes a method of unplugging a fiber opticconnector within a robotic fiber cross-connect system with a gripperincluding sensing elements at the end of a robot arm extendable along anextension axis. The method also includes translating a first connectorrow of said stacked array of connector rows so that said first connectorrow is centrally offset from other connector rows of said stacked arrayof connector rows. The method also includes translating the gripper atthe end of the robot arm in a direction normal to the connector rowsubstrate, to pass between connector track extensions onto a selected,programmably centered connector row. The method also includes monitoringthe sensing element of gripper. The method also includes based on saidmonitoring, detecting that the gripper is in close engagement with atarget connector track element of the first connector row. The methodalso includes stopping the translation of gripper upon the change instate. The method also includes translating the gripper parallel toconnector track element in a direction to engage the fiber opticconnector. The method also includes stopping the translation when thegripper sensing elements detect that the fiber optic connector isengaged within the gripper. The method also includes locking the fiberoptic connector within the gripper with a solenoid. The method alsoincludes translating the gripper parallel to connector track element andopposite the direction to unplug the fiber optic connector. The methodalso includes stopping the translation when the gripper sensing elementsdetect that the fiber optic connector is sufficiently withdrawn to beclear of the connector receptacles. The method also includes translatingthe gripper at the end of the robot arm in a direction normal to theconnector row substrate, to pass between connector track extensions.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   The method where the translating the gripper parallel to common        plane to plug in fiber is over a distance of about 12 mm.    -   The method where the gripper sensing elements are        photo-interrupter integrated circuits.    -   The method where the translating the gripper includes energizing        a stepper motor with a series of electrical pulses.    -   The method where the translating the connector row corresponds        to a linear distance of 10 to 30 mm.

Another general aspect includes a method of plugging in a fiber opticconnector within a robotic fiber cross-connect system with a gripperincluding sensing elements at the end of a robot arm extendable along anextension axis. The method also includes translating one connector rowso it centrally offset from others. The method also includes translatingthe gripper with the fiber optic connector therein at the end of therobot arm in a direction normal to the common plane, to pass betweenconnector track extensions onto a selected, programmably centeredconnector row. The method also includes monitoring the sensing elementof gripper. The method also includes detecting a change in state of asensing element, which indicates that the gripper is in close engagementwith a target connector track element of the offset connector row. Themethod also includes stopping the translation of gripper upon the changein state. The method also includes translating the gripper parallel tocommon plane in a direction to plug in the fiber optic connector intoconnector receptacle. The method also includes stopping the translationwhen the gripper sensing elements detect that the fiber optic connectoris plugged into the connector receptacle. The method also includesunlocking the fiber optic connector within the gripper by activating asolenoid. The method also includes translating the gripper parallel toconnector track element opposite the direction to plug-in the fiberoptic connector. The method also includes stopping the translation whenthe gripper sensing elements detect that gripper is sufficientlywithdrawn to be clear of the fiber optic connector. The method alsoincludes translating the gripper at the end of the robot arm in adirection normal to the connector row, to pass between connector trackextensions.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   The method where the translating the gripper parallel to common        plane to plug in fiber is over a distance of about 12 mm.    -   The method where the gripper sensing elements are        photo-interrupter integrated circuits.    -   The method where the gripper includes energizing a stepper motor        with a series of electrical pulses.    -   The method where the translating the connector row corresponds        to a linear distance of 10 to 30 mm.

Another general aspect includes an electro-mechanical interface for afiber connector gripper at the end of a robot arm to engage any of amultiplicity of fiber optic connector tracks. The electro-mechanicalinterface also includes a multiplicity of electrical connections forpower, motor and sensor lines between the robot arm and the gripper,between a pair of opposing gripper and arm circuit board assemblies,including an array of pins on a gripper circuit board and pinreceptacles on an arm circuit board. The electro-mechanical interfacealso includes a mechanical connection in which the gripper detachablyconnects to the robot arm. The electro-mechanical interface alsoincludes where the connection exhibits a pre-determined level ofmechanical compliance to allow the gripper to accommodate a slightmisalignment of the fiber optic connector track.

Another general aspect includes a gripper device with first and secondtranslating members for plugging and unplugging spring-loaded ferrulesof fiber optic connectors from mating connector receptacles. The gripperdevice also includes an actuator attached to first member. The devicealso includes a rotating shaft exiting the actuator. The device alsoincludes a gearbox with a gearbox shaft attached to the shaft, thegearbox increasing the torque output by the actuator. The device alsoincludes a double drum for winding and unwinding a flexible, low stretchdrive string under low static tension. The device also includes thesecond translating member for engaging the fiber optic connector, thesecond member including connector engagement elements that includeconnector scooping ramp features and roller elements where the connectorexperiences low frictional forces when gripper slides over connectorduring connector engagement or disengagement, where the drive stringtransfers forces from the first translating member to the secondtranslating member.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   The gripper device in which the roller elements may include 1 mm        diameter rollers with a set of ball bearing attached at both        ends of the rollers.    -   The gripper device where the actuator is a miniature dc stepper        motor with a gearbox.    -   The gripper device where the flexible, low stretch drive string        is between 0.5 and 1 mm in diameter.    -   The gripper device where the flexible string is braided to        minimize fraying.

Below is a list of gripper embodiments. Those will be indicated with theletters “G.” Whenever such embodiments are referred to, they will bedone by referring to “G” embodiments.

-   -   G1. In a fiber optic cross-connect in which a robot selectively        transports fiber optic connectors between different positions, a        fiber optic connector gripper assembly, connectable to said        robot, the gripper assembly comprising: a stepper motor drive,        responsive to command signals and mounted on a support        structure; a dual drum connected to the stepper motor drive and        rotatable about a first axis, said dual drum comprising a top        drum portion and a bottom drum portion; a plurality of bearing        shafts slidably engaged in spaced apart relation in the support        structure along axes perpendicular to the first axis; a pair of        spaced apart terminal blocks fixedly mounted on opposite ends of        the bearing shafts; and a length of drive string connected to        the dual drum, wherein a first portion of said drive string is        positioned to wind about the bottom drum portion when the drum        is rotated in first direction, and wherein an end of said first        portion of said drive string is connected to a first of said        terminal blocks, and wherein a second portion of said drive        string is positioned to unwind about the top drum portion when        the drum is rotated in a first direction, and wherein an end of        said second portion of said drive string is connected to a        spring attached to a second of said terminal blocks, and wherein        rotation of the drum in said first direction causes the pair of        spaced apart terminal blocks to move together.    -   G2. The gripper assembly of embodiment(s) G1, wherein the drive        string has a diameter of about 0.73 mm.    -   G3. The gripper assembly of any of the preceding embodiment(s),        wherein the drive string comprises a multifilament yarn spun        liquid crystal polymer.    -   G4. The gripper assembly of any of the preceding embodiment(s),        wherein the drive string is braided.    -   G5. The gripper assembly of any of the preceding embodiment(s),        wherein the drive string has at least 57 kg (125-pound) tensile        strength.    -   G6. The gripper assembly of any of the preceding embodiment(s),        wherein the drum has rounded flanges.    -   G7. The gripper assembly of any of the preceding embodiment(s),        wherein the spring enables about 6 mm of compression.    -   G8. The gripper assembly of any of the preceding embodiment(s),        wherein the drum has a mandrel and wherein the drive string        passes through a hole in the mandrel to go from the top drum        portion to the bottom drum portion.    -   G9. The gripper assembly of embodiment(s) G8, wherein a portion        of the drive string is bonded to the mandrel.    -   G10. An electrically actuated fiber optic connector gripper        device that attaches to a robot arm and generates insertion        forces sufficient to transfer a first connector with a first        ferrule in or out of a union coupler receptacle with potentially        an opposing, spring loaded ferrule therein, comprised of: a        central member attachable to the robot arm; a stepper motor        affixed to central member; a gearbox with a rotatable shaft        coupled to the stepper motor; a two-section drum, with a        clockwise spool section and an adjacent counterclockwise spool        section, having a common rotation axis coupled to the shaft of        the gearbox; and a string attached to the drum and wound in        opposite sense onto the clockwise spool section and the        counterclockwise spool section, wherein the string exits the        spool sections in substantially anti-parallel directions        perpendicular to rotation access of spool, the string affixed at        a first end to a flexible spring member and affixed at a second        end to a fixed clamp, wherein the first end and the second end        are part of a connector carrier that slides relative to central        member and retains the first connector, wherein the connector        carrier moves in a first direction when a length of string winds        onto the clockwise spool section, and a substantially identical        length of string simultaneously unwinds from the        counterclockwise spool section, and moves in the opposite        direction when the length of string unwinds from the clockwise        spool and a substantially identical length of string        simultaneously winds onto the counterclockwise spool.    -   G11. The device of embodiment(s) G10 wherein the gripper device        generates insertion forces greater than 5 N.    -   G12. The device of any of the preceding embodiment(s) G10-G11,        wherein the string comprises a high strength, small diameter,        flexible string.    -   G13. The device of any of the preceding embodiment(s) G10-G12 in        which the central member and the connector carrier are        substantially planar, rigid, and parallel to one another.    -   G14. The device of any of the preceding embodiment(s) G10-G13,        wherein electrical signals that pass between the central member        and the carrier are transferred through a flexible        multi-conductor element.    -   G15. The device of any of the preceding embodiment(s) G10-G14,        wherein the carrier includes a solenoid constructed and adapted        to lock the first connector into the carrier and to unlock the        first connector from the carrier when electrically energized.    -   G16. A gripper device with first and second translating members        for plugging and unplugging spring-loaded ferrules of fiber        optic connectors from mating connector receptacles that require        a torque impulse when plugging and unplugging the connectors,        the device comprising: an actuator attached to first member; a        rotating shaft exiting the actuator; a gearbox with a gearbox        shaft attached to the shaft, the gearbox increasing the torque        output by the actuator; and a double drum for winding and        unwinding a flexible, low stretch drive string under low static        tension, wherein the drive string is connected to a compliant        element, and wherein the torque impulse imposed on gearbox when        translating a second member is reduced by the compliant spring.    -   G17. The device of embodiment(s) G16, wherein the first and        second translating members translate substantially parallel to        one another and are connected with a pair of spaced apart linear        bearings.    -   G18. The device of any of the preceding embodiment(s) G16-G17,        wherein the second member includes one or more pulleys around        which the drive string is wrapped.    -   G19. The device of any of the preceding embodiment(s) G16-G18,        wherein the opposite ends of drive string are attached to the        first member.    -   G20. The device of any of the preceding embodiment(s) G16-G19,        wherein the opposite ends of drive string are attached to the        second member and the compliant element is a spring.    -   G21. An electro-mechanical interface for a fiber connector        gripper at the end of a robot arm, the interface comprising: an        electrical connection for power, motor and sensor lines between        the robot arm and the gripper, between a pair of opposing        gripper and arm circuit board assemblies, including an array of        pins on gripper circuit board and pin receptacles on arm circuit        board; a mechanical connection in which the gripper has a pair        of guide receptacles and the robot arm has a pair of posts,        wherein the pair of guide receptacles are plugged onto the pair        of posts, and wherein the posts and receptacles are locked into        one another with spring loaded detent that engages a pocket on        wall of posts; and an actuable locking clip to retain detent        into depression and maintain a rigid connection between gripper        and robot arm, even during motion and vibration.    -   G22. A method of unplugging a fiber optic connector within a        robotic fiber cross-connect system with a gripper including        sensing elements at the end of a robot arm extendable along an        extension axis, and with a stacked array of connector rows that        translate normal to the extension axis, each connector row        comprised of connector track extensions with connector        receptacles and a substrate, the method comprising: translating        a first connector row of said stacked array of connector rows so        that said first connector row is centrally offset from other        connector rows of said stacked array of connector rows;        translating the gripper at the end of the robot arm in a        direction normal to the connector row substrate, to pass between        connector track extensions onto a selected, programmably        centered connector row; monitoring the sensing element of        gripper; based on said monitoring, detecting that the gripper is        in close engagement with a target connector track element of the        first connector row; stopping the translation of gripper upon        the change in state; translating the gripper parallel to        connector track element in a direction to engage the fiber optic        connector; stopping the translation when the gripper sensing        elements detect that the fiber optic connector is engaged within        the gripper; locking the fiber optic connector within the        gripper with a solenoid; translating the gripper parallel to        connector track element and opposite the direction to unplug the        fiber optic connector; stopping the translation when the gripper        sensing elements detect that the fiber optic connector is        sufficiently withdrawn to be clear of the connector receptacles;        and translating the gripper at the end of the robot arm in a        direction normal to the connector row substrate, to pass between        connector track extensions.    -   G23. A method in accordance with embodiment(s) G22, wherein the        translating the gripper parallel to common plane to plug in        fiber is over a distance of about 12 mm.    -   G24. A method in accordance with embodiment(s) G22 or G23,        wherein the gripper sensing elements are photo-interrupter        integrated circuits.    -   G25. A method in accordance with any of embodiment(s) G22-G24        wherein the step of translating the gripper includes energizing        a stepper motor with a series of electrical pulses.    -   G26. A method in accordance with embodiment(s) any of        embodiment(s) G22-G25 wherein the step of translating the        connector row corresponds to a linear distance of 10 to 30 mm.    -   G27. A method of plugging in a fiber optic connector within a        robotic fiber cross-connect system with a gripper including        sensing elements at the end of a robot arm extendable along an        extension axis, and with a stacked array of connector rows that        translate normal to the extension axis, each connector row        comprised of connector track extensions with connector        receptacles in a common plane, the method comprising:        translating one connector row so it centrally offset from        others, translating the gripper with the fiber optic connector        therein at the end of the robot arm in a direction normal to the        common plane, to pass between connector track extensions onto a        selected, programmably centered connector row; monitoring the        sensing element of gripper; detecting a change in state of a        sensing element, which indicates that the gripper is in close        engagement with a target connector track element of the offset        connector row; stopping the translation of gripper upon the        change in state; translating the gripper parallel to common        plane in a direction to plug in the fiber optic connector into        connector receptacle; stopping the translation when the gripper        sensing elements detect that the fiber optic connector is        plugged into the connector receptacle; unlocking the fiber optic        connector within the gripper by activating a solenoid;        translating the gripper parallel to connector track element        opposite the direction to plug-in the fiber optic connector;        stopping the translation when the gripper sensing elements        detect that gripper is sufficiently withdrawn to be clear of the        fiber optic connector; and translating the gripper at the end of        the robot arm in a direction normal to the connector row, to        pass between connector track extensions.    -   G28. A method in accordance with embodiment(s) G27, wherein the        step of translating the gripper parallel to common plane to plug        in fiber is over a distance of about 12 mm.    -   G29. A method in accordance with embodiment(s) G27 or G28,        wherein the gripper sensing elements are photo-interrupter        integrated circuits.    -   G30. A method in accordance with any of embodiment(s) G27-G29        wherein the step of translating the gripper includes energizing        a stepper motor with a series of electrical pulses.    -   G31. A method in accordance with any of embodiment(s) G27-G30        wherein the step of translating the connector row corresponds to        a linear distance of 10 to 30 mm.    -   G32. An electro-mechanical interface for a fiber connector        gripper at the end of a robot arm to engage any of a        multiplicity of fiber optic connector tracks, the interface        comprising: a multiplicity of electrical connections for power,        motor and sensor lines between the robot arm and the gripper,        between a pair of opposing gripper and arm circuit board        assemblies, including an array of pins on a gripper circuit        board and pin receptacles on an arm circuit board; and a        mechanical connection in which the gripper detachably connects        to the robot arm, wherein the connection exhibits a        pre-determined level of mechanical compliance to allow the        gripper to accommodate a slight misalignment of the fiber optic        connector track.    -   G33. A gripper device with first and second translating members        for plugging and unplugging spring-loaded ferrules of fiber        optic connectors from mating connector receptacles, that        requires a torque impulse when plugging and unplugging the        connectors using a drive train configured to minimize wear and        maximize lifetime and torque efficiency, the gripper device        comprising: an actuator attached to first member; a rotating        shaft exiting the actuator; a gearbox with a gearbox shaft        attached to the shaft, the gearbox increasing the torque output        by the actuator; and a double drum for winding and unwinding a        flexible, low stretch drive string under low static tension; and        the second translating member for engaging the fiber optic        connector, the second member including connector engagement        elements that include connector scooping ramp features and        roller elements wherein the connector experiences low frictional        forces when gripper slides over connector during connector        engagement or disengagement, wherein the drive string transfers        forces from the first translating member to the second        translating member.    -   G34. A gripper device in accordance with embodiment(s) G33, in        which the roller elements comprise 1 mm diameter rollers with a        set of ball bearing attached at both ends of the rollers.    -   G35. A gripper device in accordance with embodiment(s) G33 or        G34, wherein the actuator is a miniature dc stepper motor with a        gearbox.    -   G36. A gripper device in accordance with any of embodiment(s)        G33-G35, wherein the flexible, low stretch drive string is        between 0.5 and 1 mm in diameter and is braided to minimize        fraying.

Robot Arm Sub-System

One general aspect includes a robotic arm assembly. The robotic armassembly also includes an inner stage removeable coupled to fiber opticconnector. The assembly also includes a middle stage with the innerstage slidable in said middle stage. The assembly also includes arolling element attached to end of middle stage. The assembly alsoincludes an outer stage with the middle stage slidable in said outerstage. The assembly also includes a flexible member connecting the innerstage, wrapping around the rolling element of middle stage, andconnected to the outer stage. The assembly also includes a motor drivethat couples translation motion to the middle stage. The assembly alsoincludes a first set of roller assemblies between inner and middlestages. The assembly also includes a second set of roller assembliesbetween the middle and outer stages.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   The robotic arm assembly where the first plurality of roller        assemblies includes hardened and ground rollers, and where the        middle stage is slidable with low friction within the outer        stage.    -   The robotic arm assembly where the lubrication element and the        spring are held in place against the middle stage by the outer        stage.    -   The robotic arm assembly where the lubrication element may        include an oil-impregnated plastic element.    -   The robotic arm assembly where the middle stage may include        case-hardened, non-magnetic stainless steel.    -   The robotic arm assembly where the middle stage is about 12.5 cm        wide, about 50 cm deep, and about 75 cm long.    -   The robotic arm assembly where the middle stage has a minimum        wall thickness of about 1 to 2 mm. The robotic arm assembly        where a preload force on the first plurality of roller        assemblies is about 10-20 N.

One general aspect includes a telescopic robot arm. The telescopic robotarm includes an outer housing with internal facing, opposing pairs ofspring loaded and fixed rollers. The arm also includes an intermediate,straight hollow member that is guided by internal facing rollers withinthe outer housing to follow a first straight path. The arm also includesan inner, straight solid member with opposing pairs of spring loaded andfixed external facing rollers. The arm also includes where the outsideof the intermediate member is guided by the internal facing rollers andthe solid member is guided within the intermediate member by theexternal facing rollers to follow a second path parallel to first path.The arm also includes where the solid member is translated by a firstflexible, elongated, low creep element that is attached to the solidmember, follows a 180 degree path over a roller affixed to a proximalend of intermediate member, and is affixed to a point on the outerhousing.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   The telescopic robot arm where the telescopic robot arm can be        removed and replaced while preserving alignment and with        features to mount a gripper at a distal end of the inner member        of the robot arm.    -   The telescopic robot arm where tension of the first and second        flexible elements is maintained.    -   The telescopic robot arm where the extension and retraction of        the telescopic robot arm is driven by a length of timing belt        connected at fixed proximal and distal ends of the intermediate,        hollow member, where the timing belt wraps around a drive pully        that is coupled to a rotating motor.    -   The telescopic robot arm where extension and retraction of the        telescopic robot arm is driven by a motorized lead screw or ball        screw with a translating nut connected at fixed proximal end of        the intermediate, hollow member.    -   The telescopic robot arm where the direction of travel of the        telescopic arm is normal to force of gravity and additionally        may include a second flexible element to extend and retract the        solid member upon translation of the intermediate hollow member.    -   The telescopic robot arm with lubrication elements attached to        the outer housing and in contact with the outer surfaces of the        intermediate hollow member in a vicinity of the internal facing,        opposing pairs of rollers.    -   The telescopic robot arm where the direction of travel of the        telescopic arm is parallel to force of gravity where a weight of        the solid member results in it extending and a motor is used to        counteract gravity to retract it.

One general aspect includes a telescopic robot module for automating afiber optic cross-connect system with a narrow, extended reachtelescopic arm having a telescopic arm extension direction, comprised ofouter, middle and inner stages that translate relative to one anotheralong a common axis, flexibly coupled wherein a multiplicity ofelectrical signals and mechanical motion is transferred from outer stageto inner stage through a fixed length, conductive first flexibleelement, a second flexible element connected at opposite ends to outerand inner stages and passing through pulley on first end of the middlestage, a third flexible element connected at opposite ends to outer andinner stage and passing through pulley on second end of the middlestage.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   The telescopic robot module where an actuator with housing fixed        to outer stage and moveable end coupled to middle stage to        impart motion to the middle stage and inner stage along the        direction parallel to telescopic arm extension direction.    -   The telescopic robot module where the inner stage moves twice as        far as the middle stage.    -   The telescopic robot module where the outer stage is attached to        a moving platform that translates the telescope arm in a        direction normal to the telescopic arm extension direction.

One general aspect includes a telescopic, robot arm device that extendsto a length. The telescopic arm also includes an outer housing withinternal facing, opposing pairs of spring loaded and fixed rollers. Thetelescopic arm also includes an intermediate, straight hollow memberthat is guided by internal facing rollers within the outer housing tofollow a first straight path. The telescopic arm also includes an inner,straight solid member with opposing pairs of spring loaded and fixedexternal facing rollers. The telescopic arm also includes where theoutside of intermediate member is guided by the internal facing rollersand the solid member is guided within the intermediate member by theexternal facing rollers to follow a second path parallel to first path.The telescopic arm also includes where a first contact pressure of theinternal facing rollers is at least three times a second contactpressure of the external facing rollers, where compliance of the arm issubstantially constant over its length of travel.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   The telescopic, robot arm device including spring loaded        lubrication blocks that contact outer surfaces of the        intermediate, straight hollow member in a vicinity of internal        facing rollers.    -   The telescopic, robot arm device where outer and inner surfaces        of the intermediate, straight hollow member are hardened        stainless steel.

Below is a list of robotic arm and related embodiments. Those will beindicated with the letters “RA.” Whenever such embodiments are referredto, they will be done by referring to “RA” embodiments.

-   -   RA37. A robotic arm assembly, in a fiber optic cross-connect in        which a robot selectively transports fiber optic connectors        between distinct positions, the robotic arm assembly comprising:        an inner stage removeable coupled to fiber optic connector; a        middle stage with the inner stage slidable in said middle stage;        a rolling element attached to end of middle stage; an outer        stage with the middle stage slidable in said outer stage; a        flexible member connecting the inner stage, wrapping around the        rolling element of middle stage and connected to the outer        stage; a motor drive that couples translation motion to the        middle stage; a first set of roller assemblies between inner and        middle stages; and a second set of roller assemblies between the        middle and outer stages.    -   RA38. The robotic arm assembly of embodiment(s) RA37, wherein        the first plurality of roller assemblies includes hardened and        ground rollers, and wherein the middle stage is slidable with        low friction within the outer stage.    -   RA39. The robotic arm assembly of embodiment(s) RA37 or RA38,        further including a spring-loaded roller lubrication mechanism        comprising:

one or more lubrication elements; and a spring positioned behind eachlubrication element, wherein the lubrication element and the spring areheld in place against the middle stage by the outer stage.

RA40. The robotic arm assembly of embodiment(s) RA39, wherein thelubrication element comprises an oil-impregnated plastic element.

-   -   RA41. The robotic arm assembly of any of the previous        embodiment(s) RA37-RA40, wherein the middle stage comprises        case-hardened, non-magnetic stainless steel.    -   RA42. The robotic arm assembly of any of the previous        embodiment(s) RA37-RA41, wherein the middle stage is about 12.5        cm wide, about 50 cm deep, and about 75 cm long.    -   RA43. The robotic arm assembly of any of the previous        embodiment(s) RA37-RA42, wherein the middle stage has a minimum        wall thickness of about 1 to 2 mm.    -   RA44. The robotic arm assembly of any of the previous        embodiment(s) RA37-RA43, wherein a preload force on the first        plurality of roller assemblies is about 10-20 N.    -   RA45. A telescopic robot arm comprising: an outer housing with        internal facing, opposing pairs of spring loaded and fixed        rollers; and an intermediate, straight hollow member that is        guided by internal facing rollers within the outer housing to        follow a first straight path; and an inner, straight solid        member with opposing pairs of spring loaded and fixed external        facing rollers, wherein the outside of the intermediate member        is guided by the internal facing rollers and the solid member is        guided within the intermediate member by the external facing        rollers to follow a second path parallel to first path, and        wherein the solid member is translated by a first flexible,        elongated, low creep element that is attached to the solid        member, follows a 180 degree path over a roller affixed to a        proximal end of intermediate member, and is affixed to a point        on the outer housing.    -   RA46. The telescopic robot arm of embodiment(s) RA45, wherein        the telescopic robot arm can be removed and replaced while        preserving alignment and with features to mount a gripper at a        distal end of the inner member of the robot arm.    -   RA47. A telescopic robot arm in accordance with embodiment(s)        RA45 or RA46 above, with a second flexible, elongated, low creep        element that is attached to the proximal end of the solid        member, extends away from the solid member in a direction        parallel but opposite to the first flexible element, wrapped to        and around a freely rotating pulley at a distal end of        intermediate member, and affixed to a point on the outer housing        wherein tension of the first and second flexible elements is        maintained.    -   RA48. The telescopic robot arm in accordance with any of the        previous embodiment(s) RA45-RA47 above, wherein the extension        and retraction of the telescopic robot arm is driven by a length        of timing belt connected at fixed proximal and distal ends of        the intermediate, hollow member, wherein the timing belt wraps        around a drive pully that is coupled to a rotating motor.    -   RA49. The telescopic robot arm in accordance with any of the        previous embodiment(s) RA45-RA48 above, wherein the extension        and retraction of the telescopic robot arm is driven by a        motorized lead screw or ball screw with a translating nut        connected at fixed proximal end of the intermediate, hollow        member.    -   RA50. The telescopic robot arm in accordance with any of the        previous embodiment(s) RA45-RA49 above, with lubrication        elements attached to the outer housing and in contact with the        outer surfaces of the intermediate hollow member in a vicinity        of the internal facing, opposing pairs of rollers.    -   RA51. The telescopic robot arm in accordance with any of the        previous embodiment(s) RA45-RA50 above, wherein the direction of        travel of the telescopic arm is parallel to force of gravity        wherein a weight of the solid member results in it extending and        a motor is used to counteract gravity to retract it.    -   RA52. The telescopic robot arm in accordance with any of the        previous embodiment(s) RA45-RA51 above, wherein the direction of        travel of the telescopic arm is normal to force of gravity and        additionally comprising a second flexible element to extend and        retract the solid member upon translation of the intermediate        hollow member.    -   RA53. A telescopic robot module for automating a fiber optic        cross-connect system with a narrow, extended reach telescopic        arm having a telescopic arm extension direction, comprised of        outer, middle and inner stages that translate relative to one        another along a common axis, flexibly coupled wherein a        multiplicity of electrical signals and mechanical motion is        transferred from outer stage to inner stage through a fixed        length, conductive first flexible element, a second flexible        element connected at opposite ends to outer and inner stages and        passing through pulley on first end of the middle stage, a third        flexible element connected at opposite ends to outer and inner        stage and passing through pulley on second end of the middle        stage.    -   RA54. A telescopic robot module in accordance with embodiment(s)        RA53, wherein an actuator with housing fixed to outer stage and        moveable end coupled to middle stage to impart motion to the        middle stage and inner stage along the direction parallel to        telescopic arm extension direction.    -   RA55. A telescopic robot module in accordance with embodiment(s)        RA53 or RA54, wherein the inner stage moves twice as far as the        middle stage.    -   RA56. A telescopic robot module in accordance with any of the        previous embodiment(s) RA53-RA55, wherein the outer stage is        attached to a moving platform that translates the telescope arm        in a direction normal to the telescopic arm extension direction.    -   RA57. A telescopic, robot arm device that extends to a length,        the robot arm comprising: an outer housing with internal facing,        opposing pairs of spring loaded and fixed rollers; an        intermediate, straight hollow member that is guided by internal        facing rollers within the outer housing to follow a first        straight path; an inner, straight solid member with opposing        pairs of spring loaded and fixed external facing rollers; and        wherein the outside of intermediate member is guided by the        internal facing rollers and the solid member is guided within        the intermediate member by the external facing rollers to follow        a second path parallel to first path, wherein a first contact        pressure of the internal facing rollers is at least three times        a second contact pressure of the external facing rollers,        wherein compliance of the arm is substantially constant over its        length of travel.    -   RA58. A telescopic, robot arm device in accordance with        embodiment(s) RA57, including spring loaded lubrication blocks        that contact outer surfaces of the intermediate, straight hollow        member in a vicinity of internal facing rollers.    -   RA59. A telescopic, robot arm device in accordance with        embodiment(s) RA57 or RA58, wherein outer and inner surfaces of        the intermediate, straight hollow member are hardened stainless        steel.

Fiber Optic Tensioning Reel Sub-System

One general aspect includes a tensioning spool apparatus for storage ofoptical fiber exhibiting reduced variation of tension during aretraction cycle versus an extension cycle of fiber over a predefinedrange of spool rotation cycles. The tensioning spool apparatus alsoincludes (a) a first spiral element may include a linear spring, alength of optical fiber characterized by an insertion loss dependent onits bend radius along a length of element, and an outer sheath with thelinear spring and the fiber therein, where the first spiral element issufficiently flexible to reduce adjacent turn interaction force andfrictional binding under bending, while being at the same timesufficiently stiff to prevent buckling of spiral during unwinding andensure that a bend radius of the optical fiber is at all locations andfor all configurations greater than a minimum bend radius specified forthe optical fiber. The apparatus also includes (b) a second spiralelement may include a flat coiled metallic spring, where the secondspiral element produces greater average torque relative to an averagetorque produced by the first spiral element. The apparatus also includes(c) a flat, non-rotating substrate in a first plane. The apparatus alsoincludes the first spiral element in a second plane. The apparatus alsoincludes the second spiral element in a third plane. The apparatus alsoincludes the first, second and third planes are parallel, and the secondplane lies between the first and third planes, and where. The apparatusalso includes the average torque transferred to the tensioning spool todrive rotation is equal to a sum of the average torque of the first andsecond spiral elements, the variation of the tension resulting primarilyfrom friction between adjacent turns of the first spiral element, anouter surface of the sheath having a low coefficient of friction withitself to minimize the variation in tension.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   An apparatus where the tension varies between 10 gm-f and 80        gm-f.    -   An apparatus where the low coefficient of friction is nominally        less than or equal to 0.25.    -   An apparatus where the minimum bend radius is approximately 5        mm.

One general aspect includes a tensioning reel system optical fiber mayinclude of two helical springs comprising a first spring and a secondspring, rotating about a common axis and producing an additive torqueabout a common axis, the first spring fixed to a central mandrel and thesecond spring fixed to an outer ring, wherein the first spring producesgreater torque than the second spring, the second spring is amulti-component assembly including an optical fiber, a straight wire andan outer sheath, and the first spring does not include an optical fiber.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   A tensioning reel system where the helical springs rotate by        identical angles about a common axis as the tensioning reel        rotates.    -   A tensioning reel system where the helical springs both unwind        or wind about a common axis as the tensioning reel rotates.    -   A tensioning reel system where the helical springs both wind to        a smaller average diameter as the optical fiber is extended from        the reel system.    -   A tensioning reel system where the system may include a        plurality of reel assemblies mounted on a sheet metal tray, each        of the plurality of reel assemblies being a tensioning spool        apparatus.    -   A tensioning reel system where the plurality of reel assemblies        may include 12 to 24 reel assemblies on the tray.

Below is a list of tensioning reel embodiments. Those will be indicatedwith the letters “TR.” Whenever such embodiments are referred to, theywill be done by referring to “TR” embodiments.

-   -   TR60. A tensioning spool apparatus for storage of optical fiber        exhibiting reduced variation of tension during a retraction        cycle versus an extension cycle of fiber over a predefined range        of spool rotation cycles, the optical fiber dynamically extended        under tension from the spool, the apparatus comprising: (A) a        first spiral element comprising a linear spring, a length of        optical fiber characterized by an insertion loss dependent on        its bend radius along a length of element, and an outer sheath        with the linear spring and the fiber therein, wherein the first        spiral element is sufficiently flexible to reduce adjacent turn        interaction force and frictional binding under bending, while        being at the same time sufficiently stiff to prevent buckling of        spiral during unwinding and ensure that a bend radius of the        optical fiber is at all locations and for all configurations        greater than a minimum bend radius specified for the optical        fiber; (B) a second spiral element comprising a flat coiled        metallic spring, wherein the second spiral element produces        greater average torque relative to an average torque produced by        the first spiral element; and (C) a flat, non-rotating substrate        in a first plane, wherein the first spiral element in a second        plane, the second spiral element in a third plane, and the        first, second and third planes are parallel, and the second        plane lies between the first and third planes, and wherein the        average torque transferred to the tensioning spool to drive        rotation is equal to a sum of the average torque of the first        and second spiral elements, the variation of said tension        resulting primarily from friction between adjacent turns of the        first spiral element, an outer surface of the sheath having a        low coefficient of friction with itself to minimize the        variation in tension.    -   TR61. An apparatus in accordance with embodiment(s) TR60,        wherein the tension varies between 10 gm-f and 80 gm-f.    -   TR62. An apparatus in accordance with embodiment(s) TR60 or        TR61, wherein the low coefficient of friction is nominally less        than or equal to 0.25.    -   TR63. An apparatus in accordance with embodiment(s) TR60,        wherein the minimum bend radius is approximately 5 mm.    -   TR64. A tensioning reel system optical fiber comprised of two        helical springs, comprising a first spring and a second spring,        rotating about a common axis and producing an additive torque        about a common axis, the first spring fixed to a central mandrel        and the second spring fixed to an outer ring, wherein the first        spring produces greater torque than the second spring, the        second spring is a multi-component assembly including an optical        fiber, a straight wire and an outer sheath, and the first spring        does not include an optical fiber.    -   TR65. A tensioning reel system in accordance with embodiment(s)        TR64, wherein the helical springs rotate by identical angles        about a common axis as the tensioning reel rotates.    -   TR66. A tensioning reel system in accordance with embodiment(s)        TR64 or TR65, wherein the helical springs both unwind or wind        about a common axis as the tensioning reel rotates.    -   TR67. A tensioning reel system in accordance with any of        embodiment(s) TR64 or TR65, including a circular mandrel on        which optical fiber can be repeatedly wound and unwound, wherein        the helical springs both wind to a smaller average diameter as        the optical fiber is extended from the reel system.    -   TR68. A system comprising a plurality of reel assemblies mounted        on a sheet metal tray, each of said plurality of reel assemblies        being a tensioning spool apparatus according to any of        embodiment(s) TR60 or TR68.    -   TR69. The system of embodiment(s) TR68, wherein the plurality of        reel assemblies comprises 12 to 24 reel assemblies on said tray.

Fiber Optic Tensioning Pulley Sub-System

One general aspect includes a system of fiber optic cable length buffersthat tension fiber optic cables. The system of fiber optic cable lengthbuffers also includes a central, stacked linear array of flexible, lowfriction through guides attached to a common substrate. The system alsoincludes a multiplicity of the length buffers arrayed on the commonsubstrate. The system also includes where the length buffers eachinclude a spring-loaded moving sled with a stacked multiplicity offreely rotating pulleys on a moving common shaft, and a spaced-apartfixed common shaft with an equal multiplicity of freely rotating pulleysthereon. The system also includes where a fiber optic cable wraps in arepeated circuit around opposing sets of pulleys on the moving commonshaft and on the fixed common shaft and the fiber optic cable is routedthrough one of the low friction through guides to a fiber opticconnector at a distal fiber end.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   The system of fiber optic cable length buffers where a length of        fiber extendable from the length buffers is approximately equal        to a number of circuits multiplied by the maximum distance        between the moving and fixed common shaft.    -   The system where the spring-loaded moving sled is attached to a        pair of power springs at one end and attached to the common        substrate at the other end and extends in opposition from their        fixed housing.    -   The system where an average tension of the fiber optic cable is        equal to a total retraction force of the pair of power springs        divided by a number of circuits.    -   The system where the distal fiber end is terminated in a        connector that is connected and/or disconnected by a robot        system.    -   The system where the distal fiber end connector end face is        cleanable by the robot system swiping the end face across        cleaning fabric.    -   The system where the outer diameter of the individual low        friction through guides is less than or equal to 1.0 mm to        enable a high density of arrayed fiber optical cable length        buffers.    -   The system where the outer diameter of the fiber optic cable is        less than or equal to 0.5 mm to enable a high density of arrayed        fiber optical cable length buffers.

Another general aspect includes a method of maintaining tension ofoptical fiber cables extendable from arrayed spools. The method ofmaintaining tension of optical fiber cables also includes extending afirst optical fiber cable of the optical fiber cables from the arrayedspools by robot actuator. The method also includes sliding the firstoptical fiber cable through one of an array of flexible guides. Themethod also includes rotating a roller attached to a rotary encoder togenerate encoder pulses. The method also includes counting the encoderpulses. The method also includes pulling the optical fibers cablewrapped around spools in multiple circuits on a sled traveling betweentwo endpoints. The method also includes rotating arrayed spools on thesled with different rotation speeds. The method also includestranslating a sled along a straight path due to dynamic extension forceof optical fiber cables wrapped around spools of the sled. The methodalso includes pulling one or more springs attached at one end to thesled from their housing to impart a restoring force that maintains thetension.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   The method where the tension is in the range of 20 gm-f to 50        gm-f on average, and where the tension increases as a length of        the first optical fiber cable extended increases.    -   The method where the method may include comparing a number of        encoder pulses to a calculated extension length to verify that        the first fiber optic cable is properly extended or retracted.    -   The method where the method may include driving the robot        actuator so that the travel of the sled is a fraction of the        travel of the robot actuator.

Another general aspect includes a fiber optic cable length buffer devicethat auto-tensions a moveable end of an optical fiber cable that isextendable from the length buffer and opposite a fixed end of theoptical fiber cable. The fiber optic cable length buffer device alsoincludes a spring-loading translating sled with a multiplicity of freelyrotating pulleys about a common first shaft affixed to the translatingsled. The device also includes a spaced-apart fixed common second shaftwith an equal multiplicity of freely rotating pulleys thereon. Thedevice also includes where the fiber optic cable wraps in a repeatedcircuit around opposite pairs of pulleys on the common first shaft andon the common second shaft, and the moveable end of fiber optic cable isrouted through a low friction through guide to a fiber optic connector,the force produced by spring-loading on sled equal to an integermultiple of the tension force imparted on the moveable end of theoptical fiber cable.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   The buffer device where a ratio of a pully's outer diameter to        the shaft's outer diameter is about 10 to 1.    -   The buffer device where a tension force imparted on the moveable        end of the optical fiber cable is in the range of 10 gm-f to 50        gm-f.    -   The buffer device where the optical fiber cable has a low        friction, wear resistant protective covering with outer diameter        of 0.25 to 0.5 mm.    -   The buffer device where the optical fiber cable is may include        of one or more individual optical fibers.

Below is a list of tensioning pulley embodiments. Those will beindicated with the letters “TP.” Whenever such embodiments are referredto, they will be done by referring to “TP” embodiments.

-   -   TP70. A system of fiber optic cable length buffers that tension        fiber optic cables, each fiber optic cable with distal and        proximal ends and extendable from the length buffer, the system        comprising: a central, stacked linear array of flexible, low        friction through guides attached to a common substrate; and a        multiplicity of the length buffers arrayed on the common        substrate, wherein the length buffers each include a        spring-loaded moving sled with a stacked multiplicity of freely        rotating pulleys on a moving common shaft, and a spaced-apart        fixed common shaft with an equal multiplicity of freely rotating        pulleys thereon, and wherein a fiber optic cable wraps in a        repeated circuit around opposing sets of pulleys on the moving        common shaft and on the fixed common shaft and said fiber optic        cable is routed through one of the low friction through guides        to a fiber optic connector at a distal fiber end.    -   TP71. The system of fiber optic cable length buffers of        embodiment(s) TP70, wherein a length of fiber extendable from        the length buffers is approximately equal to a number of        circuits multiplied by the maximum distance between the moving        and fixed common shaft.    -   TP72. The system of fiber optic cable length buffers of        embodiment(s) TP70 or TP71, wherein the spring-loaded moving        sled is attached to a pair of power springs at one end and        attached to the common substrate at the other end and extends in        opposition from their fixed housing.    -   TP73. The system of fiber optic cable length buffers of any of        the preceding embodiment(s) TP70-TP72, wherein an average        tension of the fiber optic cable is equal to a total retraction        force of the pair of power springs divided by a number of        circuits.

TP74. The system of fiber optic cable length buffers of any of thepreceding embodiment(s) TP70-TP73, wherein the distal fiber end isterminated in a connector that is connected and/or disconnected by arobot system.

-   -   TP75. The system of fiber optic cable length buffers of any of        the preceding embodiment(s) TP70-TP74, wherein the distal fiber        end connector end face is cleanable by the robot system swiping        the end face across cleaning fabric.    -   TP76. The system of fiber optic cable length buffers of any of        the preceding embodiment(s) TP70-TP75, wherein the outer        diameter of the individual low friction through guides is less        than or equal to 1.0 mm to enable a high density of arrayed        fiber optical cable length buffers.    -   TP77. The system of fiber optic cable length buffers of any of        the preceding embodiment(s) TP70-TP76, wherein the outer        diameter of the fiber optic cable is less than or equal to 0.5        mm to enable a high density of arrayed fiber optical cable        length buffers.    -   TP78. A method of maintaining tension of optical fiber cables        extendable from arrayed spools, the method comprising: extending        a first optical fiber cable of the optical fiber cables from the        arrayed spools by robot actuator; sliding the first optical        fiber cable through one of an array of flexible guides; rotating        a roller attached to a rotary encoder to generate encoder        pulses; counting the encoder pulses; pulling the optical fiber        cable wrapped around spools in multiple circuits on a sled        traveling between two endpoints; rotating arrayed spools on the        sled with different rotation speeds; translating a sled along a        straight path due to dynamic tension force of optical fiber        cables wrapped around spools of the sled; and pulling one or        more springs attached at one end to the sled from their housing        to impart a restoring force that maintains the tension.    -   TP79. The method of embodiment(s) TP78 wherein the tension is in        the range of 20 gm-f to 50 gm-f on average, and wherein the        tension increases as a length of the first optical fiber cable        extended increases.    -   TP80. The method of embodiment(s) TP78 or TP78, further        comprising: comparing a number of encoder pulses to a calculated        extension length to verify that the first fiber optic cable is        properly extended or retracted.    -   TP81. The method of any of the preceding embodiment(s)        TP78-TP80, further comprising: driving the robot actuator so        that the travel of the sled is a fraction of the travel of the        robot actuator.    -   TP82. A fiber optic cable length buffer device that        auto-tensions a moveable end of an optical fiber cable that is        extendable from the length buffer and opposite a fixed end of        the optical fiber cable, wherein the length buffer comprises: a        spring-loading translating sled with a multiplicity of freely        rotating pulleys about a common first shaft affixed to the        translating sled; and a spaced-apart fixed common second shaft        with an equal multiplicity of freely rotating pulleys thereon,        wherein the fiber optic cable wraps in a repeated circuit around        opposite pairs of pulleys on the common first shaft and on the        common second shaft, and the moveable end of fiber optic cable        is routed through a low friction through guide to a fiber optic        connector, the force produced by spring-loading on sled equal to        an integer multiple of the tension force imparted on the        moveable end of the optical fiber cable.    -   TP83. The buffer device of embodiment(s) TP82, wherein a ratio        of a pully's outer diameter to the shaft's outer diameter is        about 10 to 1.    -   TP84. The buffer device of embodiment(s) TP82 or TP83, wherein a        tension force imparted on the moveable end of the optical fiber        cable is in the range of 10 gm-f to 50 gm-f.    -   TP85. The buffer device of any of the preceding embodiment(s)        TP82-TP84, wherein the optical fiber cable has a low friction,        wear resistant protective covering with outer diameter of 0.25        to 0.5 mm.    -   TP86. The buffer device of any of the preceding embodiment(s)        TP82-TP85, wherein the optical fiber cable is comprised of one        or more individual optical fibers.

Cleaning Cartridge Sub-System

One general aspect comprises a device that includes a drive mechanism; apressure sensor; a source spool of fabric; a take-up spool operativelyconnected to the drive mechanism; and a plurality of guide rollers toguide the fabric past the pressure sensor to the take-up spool. Thedevice also includes where contact of a fiber connector tip on thepressure sensor causes the drive mechanism, after a predetermined delay,to rotate the take-up spool and advance a predetermined amount of thefabric from the source spool to the take-up spool.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   The device may include: a linear actuator; a lever arm; and a        time-delay circuit, and where a voltage change across the        pressure sensor triggers the time-delay circuit to, after the        predetermined delay, switch on drive current to the linear        actuator for a predetermined amount of time, where the linear        actuator drives the lever arm which rotates a drive shaft        through opposing one-way needle bearings.    -   The device where the predetermined delay is 3 to 4 seconds.    -   The device where the predetermined amount of the fabric is about        1.5 mm to 3 mm of the fabric.    -   The device where the fabric may include a cleaning fabric.    -   The device where the device may include an encoder, connected to        the source spool, to determine/confirm advancement of the fabric        from the source spool to the take-up spool.    -   The device where the encoder detects the advance of fabric. The        device where a signal from the encoder is processed to provide        an estimate of remaining fabric on the source spool, and/or an        indication of finished fabric on the source spool.    -   The device where the drive mechanism may include a clutch. The        device where the device is constructed and adapted to attach to        a robot module in an automated fiber optic cross-connect system.

Another general aspect includes a method in an automated fiber opticcross-connect system. The method also includes a gripper engaging afiber connector tip with a cleaning fabric and activating a touchsensor. The method also includes a voltage change across the touchsensor triggering a time-delay circuit. The method also includes after apredetermined delay, the time-delay circuit switching on drive currentto a linear actuator for a predetermined amount of time. The method alsoincludes the linear actuator driving a lever which rotates a drive shaftthrough opposing one-way needle bearings, where rotation of the driveshaft rotates a fabric feed roller.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   The method where the predetermined delay is about 3-5 seconds.    -   The method where the predetermined amount of time is about 5        seconds.    -   The method where the rotation of the drive shaft causes the        cleaning fabric to advance about 1.5 mm to 3 mm.

Another general aspect includes a cleaning cartridge system fordispensing and usage monitoring of fiber end face cleaning fabric. Thecleaning cartridge system also includes a spool of cleaning fabric. Thesystem also includes an actuator that drives a fabric advance roller.The system also includes a pressure sensor that detects when a fiber endface is in contact with fabric and outputs a contact-indicating signal.The system also includes a clutch attached to a shaft of the spool tomaintain tension on the cleaning fabric. The system also includes arotary encoder attached to shaft of the spool to measure advance of thecleaning fabric. The system also includes an internal control circuitthat drives the actuator to advance the cleaning fabric in time-relationto the contact-indicating signal. The system also includes an externalcontroller that measures encoder output signal to verify proper advanceof the cleaning fabric and consumption of the cleaning fabric over time.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   The cleaning cartridge system further including an optical        inspection microscope to verify cleanliness of an optical fiber        end face after cleaning.    -   The cleaning cartridge system further including an optical        time-domain reflectometer, optical power meter and detector, or        optical coherence domain reflectometer to measure insertion loss        and/or backreflection at the fiber end face and verify        cleanliness of an optical fiber end face after cleaning by        ensuring backreflection is less than −45 dB and/or insertion        loss less than 0.5 dB.

Another general aspect includes a method of cleaning an optical fiberend face with a cleaning fabric in an automated cross-connect systemthat reconfigures optical fiber end faces among a multiplicity ofreceiving receptacles. The method also includes energizing an electricalactuator. The method also includes rotating a fabric advance roller totranslate fabric ribbon. The method also includes unspooling fabricribbon partially from fabric ribbon source spool. The method alsoincludes advancing a pre-determined section of fabric to present anunused section of fabric at a cleaning element. The method also includescounting encoder pulses generated when advancing the fabric. The methodalso includes waiting for the fabric advance to complete based on anencoder pulse count. The method also includes contacting the opticalfiber end face substantially normal to a surface of the fabric. Themethod also includes detecting contact of the optical fiber end face onfabric using a force or pressure sensor. The method also includesswiping the optical fiber end face in a direction substantially normalto fabric ribbon length. The method also includes withdrawing thecleaned optical fiber end face from cleaning element. The method alsoincludes plugging the optical fiber end face into one of themultiplicity of receiving receptacles.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   The method where the method may include measuring a        backreflection of the cleaned optical fiber end face to verify        cleaning.    -   The method where the method may include repeating acts in the        method if the backreflection of the cleaned optical fiber end        face exceeds a given threshold.    -   The method where the repeating may include repeating all acts in        the method.    -   The method where the given threshold equals −50 dB.    -   The method where the method may include inspecting the optical        fiber end face for cleanliness using an optical microscope and        image processing system to identify contamination.    -   The method where the method may include repeating steps in the        process if the image processing system determines that the        optical fiber end face is not adequately cleaned.    -   The method where the repeating may include repeating all steps        in the process.

One general aspect includes a method of maintaining low loss physicalfiber optic connections in an automated cross-connect system thatreconfigures optical fiber end faces among a multiplicity of receivingreceptacles. The method of maintaining low loss physical fiber opticconnections also includes (a) cleaning the fiber optic connection. Themethod may also include (b) plugging in the fiber optic connection intoone of the multiplicity of receiving receptacles. The method may alsoinclude (c) testing a resulting connection by launching a pulse throughthe fiber optic connection and measuring a backreflection correspondingto the resulting connection. The method may also include (d) determininga backreflection level from the fiber optic connection and checking thatthe backreflection level is less than −50 dB, and if the backreflectionis greater than −50 dB, repeating acts (a)-(d).

-   -   Implementations may include one or more of the following        features, alone and/or in combination(s): The method where the        pulse has a duration of less than 10 ns.    -   The method where the pulse is at a wavelength between 1300 nm        and 1650 nm.

Below is a list of cleaning cartridge embodiments. Those will beindicated with the letters “CC.” Whenever such embodiments are referredto, they will be done by referring to “CC” embodiments.

-   -   CC87. A device comprising: a drive mechanism; a pressure sensor;        a source spool of fabric; a take-up spool operatively connected        to the drive mechanism; and a plurality of guide rollers to        guide the fabric past the pressure sensor to the take-up spool,        wherein contact of a fiber connector tip on the pressure sensor        causes the drive mechanism, after a predetermined delay, to        rotate the take-up spool and advance a predetermined amount of        the fabric from the source spool to the take-up spool.    -   CC88. The device of claim CC87, further comprising: a linear        actuator; a lever arm; and a time-delay circuit, and wherein a        voltage change across the pressure sensor triggers the        time-delay circuit to, after said predetermined delay, switch on        drive current to the linear actuator for a predetermined amount        of time, wherein the linear actuator drives the lever arm which        rotates a drive shaft through opposing one-way needle bearings.    -   CC89. The device of claims CC87 or CC88, wherein the        predetermined delay is 3 to 4 seconds.    -   CC90. The device of claims CC87 or CC88, wherein the        predetermined amount of the fabric is about 1.5 mm to 3 mm of        the fabric.    -   CC91. The device of claims CC87 or CC88, wherein the fabric        comprises a cleaning fabric.    -   CC92. The device of CC87 or CC88, further comprising an encoder,        connected to the source spool, to determine/confirm advancement        of the fabric from the source spool to the take-up spool.

CC93. The device of claim CC92, wherein the encoder detects the advanceof fabric.

-   -   CC94. The device of claim CC92, wherein a signal from the        encoder is processed to provide an estimate of remaining fabric        on the source spool, and/or an indication of finished fabric on        the source spool.    -   CC95. The device of claims CC87 or CC88, wherein the drive        mechanism comprises a clutch.    -   CC96. The device of claim CC87, constructed and adapted to        attach to a robot module in an automated fiber optic        cross-connect system.    -   CC97. A method, in an automated fiber optic cross-connect        system, the method comprising: a gripper engaging a fiber        connector tip with a cleaning fabric and activating a touch        sensor; a voltage change across the touch sensor triggering a        time-delay circuit; after a predetermined delay, the time-delay        circuit switching on drive current to a linear actuator for a        predetermined amount of time; and the linear actuator driving a        lever which rotates a drive shaft through opposing one-way        needle bearings, wherein rotation of the drive shaft rotates a        fabric feed roller.    -   CC98. The method of claim CC97, wherein the predetermined delay        is about 3-5 seconds.    -   CC99. The method of claim CC97, wherein the predetermined amount        of time is about 5 seconds.    -   CC100. The method of claim CC97, wherein rotation of the drive        shaft causes the cleaning fabric to advance about 1.5 mm to 3        mm.    -   CC101. A cleaning cartridge system for dispensing and usage        monitoring of fiber end face cleaning fabric, the cartridge        system comprising: a spool of cleaning fabric; an actuator that        drives a fabric advance roller; a pressure sensor that detects        when a fiber end face is in contact with fabric and outputs a        contact-indicating signal; a clutch attached to a shaft of the        spool to maintain tension on the cleaning fabric; a rotary        encoder attached to shaft of the spool to measure advance of the        cleaning fabric; an internal control circuit that drives the        actuator to advance the cleaning fabric in time-relation to the        contact-indicating signal; and an external controller that        measures encoder output signal to verify proper advance of the        cleaning fabric and consumption of the cleaning fabric over        time.    -   CC102. The cleaning cartridge system of claim CC101, further        including an optical inspection microscope to verify cleanliness        of an optical fiber end face after cleaning.    -   CC103. The cleaning cartridge system of claim CC102, further        including an optical time-domain reflectometer, optical power        meter and detector, or optical coherence domain reflectometer to        measure insertion loss and/or backreflection at the fiber end        face and verify cleanliness of an optical fiber end face after        cleaning by ensuring backreflection is less than −45 dB and/or        insertion loss less than 0.5 dB.    -   CC104. A method of cleaning an optical fiber end face with a        cleaning fabric in an automated cross-connect system that        reconfigures optical fiber end faces among a multiplicity of        receiving receptacles, the method comprising: energizing an        electrical actuator; rotating a fabric advance roller to        translate fabric ribbon; unspooling fabric ribbon partially from        fabric ribbon source spool; advancing a pre-determined section        of fabric to present an unused section of fabric at a cleaning        element; counting encoder pulses generated when advancing the        fabric; waiting for the fabric advance to complete based on an        encoder pulse count; contacting the optical fiber end face        substantially normal to a surface of the fabric; detecting        contact of the optical fiber end face on fabric using a force or        pressure sensor; swiping the optical fiber end face in a        direction substantially normal to fabric ribbon length;        withdrawing the cleaned optical fiber end face from cleaning        element; and plugging the optical fiber end face into one of the        multiplicity of receiving receptacles.    -   CC105. The method of claim CC104, further comprising: measuring        a backreflection of the cleaned optical fiber end face to verify        cleaning.    -   CC106. The method of claim CC105, further comprising: repeating        acts in the method if the backreflection of the cleaned optical        fiber end face exceeds a given threshold.    -   CC107. The method of claim CC106, wherein said repeating        comprises repeating all acts in the method.    -   CC108. The method of claim CC106, wherein the given threshold        equals −50 dB.    -   CC109. The method of claim CC104, further comprising: inspecting        the optical fiber end face for cleanliness using an optical        microscope and image processing system to identify        contamination.    -   CC110. The method of claim CC109, further comprising: repeating        steps in the process if the image processing system determines        that the optical fiber end face is not adequately cleaned.

CC111. The method of claim CC110, wherein said repeating comprisesrepeating all steps in the process.

-   -   CC112. A method of maintaining low loss physical fiber optic        connections in an automated cross-connect system that        reconfigures optical fiber end faces among a multiplicity of        receiving receptacles, the method comprising: (A) cleaning the        fiber optic connection; (B) plugging in the fiber optic        connection into one of the multiplicity of receiving        receptacles; (C) testing a resulting connection by launching a        pulse through the fiber optic connection and measuring a        backreflection corresponding to the resulting connection;        and (D) determining a backreflection level from the fiber optic        connection and checking that the backreflection level is less        than −50 dB, and if the backreflection is greater than −50 dB,        repeating acts (A)-(D).    -   CC113. The method of claim CC112, wherein the pulse has a        duration of less than 10 ns.    -   CC114. The method of claim CC112, wherein the pulse is at a        wavelength between 1300 nm and 1650 nm.

System Combination of Replaceable Sub-Systems

One general aspect includes a robotic fiber optic cross-connect systemfor configuring signal transmission of fiber interconnects across anarray of bi-directional connections and comprising a multiplicity ofreplaceable sub-systems, wherein a reconfiguration utilizes a multi-stepprocess of mechanical rearrangement based on anti-collision algorithmand electronic sensing, and wherein an arbitrary reconfiguration of thearray of bi-directional connections takes at least 30 seconds tocomplete the multi-step process.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   The system where each subsystem can be replaced without        interruption of transmission of signals through the        cross-connect system.    -   The system where each subsystem can be replaced within about 60        minutes without interruption of transmission of signals through        the cross-connect system.    -   The system where the replaceable sub-systems include a        controller subsystem, robot subsystem, a gripper subsystem, a        cleaning cartridge subsystem, and a fiber tensioning subsystem.

One general aspect includes a robotic fiber optic cross-connect systemfor configuring connectivity of fiber interconnects across an array ofconnections. The robotic fiber optic cross-connect system also includesa controller executing a knots, braids and strands (KBS) algorithm andmachine instructions. The system also includes a robot subsystem with atranslatable platform carrying an extendable robot arm that extendsalong a first axis with a gripper attached to end of arm. The systemalso includes a cleaning cartridge attached to a translatable platform.The system also includes a multiplicity of fibers with connectors thatare carried by the gripper, each fiber independently tensioned andretracted within an arrayed storage and tensioning device incorporatinga multiplicity of spring-powered retractors and a linear backbone of lowfriction, flexible guides along a second axis.

The system also includes where the first axis and the second axis aresubstantially parallel.

Implementations may include one or more of the following features, aloneand/or in combination(s):

-   -   The system where the extendable robot arm is a multi-stage unit        with an outer stage attached to translatable platform, a middle        stage translating within the outer stage and an inner stage        sliding within the middle stage and with a gripper attached at        one end of the inner stage.    -   The system where the system further including a multiplicity of        optical power monitor test ports to measure optical power within        any fiber interconnect.    -   The system where the system further including a multiplicity of        optical time domain reflectometer test ports to measure        insertion loss, backreflection and length along an extended and        external optical fiber connected to any fiber interconnect.    -   The system where the system further including a multiplicity of        light source test ports to launch optical power into an extended        and external optical fiber connected to any fiber interconnect.

Below is a list of tensioning reel embodiments. Those will be indicatedwith the letters “COMB.” Whenever such embodiments are referred to, theywill be done by referring to “COMB” embodiments.

-   -   COMB115. A robotic fiber optic cross-connect system for        configuring signal transmission of fiber interconnects across an        array of bi-directional connections and comprising a        multiplicity of replaceable sub-systems, wherein a        reconfiguration utilizes a multi-step process of mechanical        rearrangement based on anti-collision algorithm and electronic        sensing, and wherein an arbitrary reconfiguration of the array        of bi-directional connections takes at least 30 seconds to        complete the multi-step process.    -   COMB116. The system of embodiment(s) COMB115, wherein each        subsystem can be replaced without interruption of transmission        of signals through the cross-connect system.    -   COMB117. The system of embodiment(s) COMB115 or COMB116, wherein        each subsystem can be replaced without interruption of        transmission of signals through the cross-connect system.    -   COMB118. The system of any of the preceding embodiment(s)        COMB115-COMB117, wherein each subsystem can be replaced within        about 60 minutes without interruption of transmission of signals        through the cross-connect system.    -   COMB119. A system in accordance with any of the preceding        embodiment(s) COMB115-COMB118, wherein the replaceable        sub-systems include a controller subsystem, robot subsystem, a        gripper subsystem, a cleaning cartridge subsystem, and a fiber        tensioning subsystem.    -   COMB120. A robotic fiber optic cross-connect system for        configuring connectivity of fiber interconnects across an array        of connections, the system comprising: a controller executing a        Knots, Braids and Strands (KBS) algorithm and machine        instructions; a robot subsystem with a translatable platform        carrying an extendable robot arm that extends along a first axis        with a gripper attached to end of arm; a cleaning cartridge        attached to a translatable platform; and a multiplicity of        fibers with connectors that are carried by the gripper, each        fiber independently tensioned and retracted within an arrayed        storage and tensioning device incorporating a multiplicity of        spring-powered retractors and a linear backbone of low friction,        flexible guides along a second axis, wherein the first axis and        the second axis are substantially parallel.    -   COMB121. The system of embodiment(s) COMB120, wherein the        extendable robot arm is a multi-stage unit with an outer stage        attached to translatable platform, a middle stage translating        within the outer stage and an inner stage sliding within the        middle stage and with a gripper attached at one end of the inner        stage.    -   COMB122. The system of embodiment(s) COMB120 or COMB121, further        including a multiplicity of optical power monitor test ports to        measure optical power within any fiber interconnect.    -   COMB123. The system of any of the preceding embodiment(s)        COMB120-COMB122, further including a multiplicity of optical        time domain reflectometer test ports to measure insertion loss,        backreflection and length along an extended and external optical        fiber connected to any fiber interconnect.    -   COMB124. The system of any of the preceding embodiment(s)        COMB120-COMB123, further including a multiplicity of light        source test ports to launch optical power into an extended and        external optical fiber connected to any fiber interconnect.

Embodiment(s) in Combination

Another general aspect includes one or more of the following, aloneand/or in combination(s):

-   -   any gripper device according to embodiment(s) G1-G36; and/or    -   any robot arm sub-system according to embodiment(s) RA37-RA59;        and/or    -   any fiber optic tensioning reel sub-system according to        embodiment(s) TR60-TR69; and/or    -   any fiber optic tensioning pulley sub-system according to        embodiment(s) TP70-TP86; and/or    -   any cleaning cartridge sub-system according to embodiment(s)        CC87-CC114; and/or    -   any system combination of replaceable sub-systems according to        embodiment(s) COMB115-COMB124.

DESCRIPTION OF THE DRAWINGS

Objects, features, and characteristics of the present invention as wellas the methods of operation and functions of the related elements ofstructure, and the combination of parts and economies of manufacture,will become more apparent upon consideration of the followingdescription and the appended claims with reference to the accompanyingdrawings, all of which form a part of this specification.

Gripper Sub-System

FIGS. 1A-1F, 2A-2D, 3, 4A-4E, and 5A-5B depict aspects of a gripperassembly according to exemplary embodiments hereof;

FIG. 6A is a flowchart depicting aspects of an unplug operation of thegripper assembly according to exemplary embodiments hereof,

FIG. 6B is a flowchart depicting aspects of a plug-in operation of thegripper assembly according to exemplary embodiments hereof; and

FIGS. 7A-7B illustrate a quick-disconnect electro-mechanical interfacefor the gripper assembly according to exemplary embodiments hereof.

Robot Arm Sub-System

FIGS. 8, 9A, and 9B depict aspects of a robotic arm according toexemplary embodiments hereof;

FIGS. 10A-10L depict aspects of a robot leveling mechanism according toexemplary embodiments hereof; and

FIGS. 11A-11D are diagrams of a telescopic robotic arm that extends andretracts along a substantially horizontal direction without theassistance of gravity.

Cleaning Cartridge Sub-System

FIGS. 12-13, 14A-14L, 15A-15F, 16, and 17A-17B depict aspects of acleaning cartridge system according to exemplary embodiments hereof and

FIG. 18 is a flowchart depicting operation of a cleaning cartridgesystem according to exemplary embodiments hereof.

Fiber Optic Tensioning Reel Sub-System

FIG. 19 depicts aspects of an exploded view of a reel system accordingto exemplary embodiments hereof;

FIGS. 20A-20C depict top, side, and bottom views of aspects of a reelsystem according to exemplary embodiments hereof; and

FIGS. 21-22 depict aspects of a reel system according to exemplaryembodiments hereof.

Fiber Optic Tensioning Pulley Sub-System

FIGS. 23A-23C illustrate a top and perspective view of aspects of thethree-dimensional arrangement of pulleys on a common substrate accordingto exemplary embodiments hereof;

FIGS. 24A-24B depict aspects of an example moveable pulley systemaccording to exemplary embodiments hereof;

FIGS. 25A-25B depict aspects an example of an electronic pulley rotationdetection subsystem; and

FIG. 26 is a flow chart of the tensioning process according to exemplaryembodiments hereof.

ROBOTIC CROSS-CONNECT SYSTEM

FIG. 27 is a sub-system diagram of the automated cross-connect systemaccording to exemplary embodiments hereof.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EXEMPLARY EMBODIMENTS

A robotic cross-connect system with compact gripper at the end of atelescopic arm to carry a fiber optic connector at the end of anextendable, tensioned fiber retained within a slack management systemthat prevents entanglement with other tensioned fibers sharing the samevolume is disclosed. Methods of plugging, unplugging, cleaning, andtensioning the optical fibers terminated in connectors are alsodescribed.

GRIPPER SUB-SYSTEM

The gripper sub-system disclosed herein has unique design requirementsto ensure that fiber interconnections can be provisioned andreprovisioned over the lifetime of the system without interruption orfaults, on demand even after extended periods of inactivity, in a highlycompact form factor to fit within the dense fiber interconnect volumeinside the cross-connect system. The service lifetime is typically inexcess of 10 years. The gripper sub-system must be easily replaceablewithout the need for skilled labor.

FIG. 1A depicts aspects of a gripper assembly 1100 according toexemplary embodiments hereof. FIG. 1B is an enlarged and partiallyexposed version of the gripper assembly 1100 of FIG. 1A, between thelines X-X′ and Y-Y′. With reference to FIGS. 1A-1F a gripper assembly1100 for use, e.g., in a high-reliability robot cross-connect system isdescribed. The gripper assembly 1100 may be positioned, e.g., at the endof telescopic arm or the like (not shown), and may be moved, e.g., usinga two-axis robotic actuation system, and the gripper is actuated by anexternal electronic controller (e.g., as shown in U.S. Pat. No.10,345,526, the entire contents of which are hereby fully incorporatedherein by reference for all purposes).

The gripper assembly 1100 comprises two closely adjacent printed circuitboards (PCBs), a lower printed circuit board 1102 and an upper printedcircuit board 1104 lying in a narrow vertical plane. The gripperassembly 1100 also includes multiple sensors (including unplug sensor1302, allocate sensor 1304, unallocate sensor 1306, row sensor 1308, andsolenoid latch sensor 1310) and actuators, the signals of which areelectrically interfaced to an external circuit through a connector.Electrical signals between the two printed circuit boards may betransferred by a flexible ribbon cable 1101 (shown in FIG. 1A) that isable to flex, and the printed circuit boards translate in directionnominally perpendicular to length of ribbon cable. The individualjacketed wires of the ribbon cable are singulated along a length in asection at the middle of ribbon. This facilitates the relative movementof the wires by reducing the stiffness of cable in the translationdirection.

An exemplary gripper assembly 1100 includes a motor 1106, for example apermanent magnet stepper motor with integral gearbox 1107 which rotatesa gripper drive dual drum 1108 (via shaft 1109). The dual drum 1108(e.g., as shown, e.g., in FIGS. 2A-2D) has a top drum 1108-T and abottom drum 1108-B. The top and bottom drums preferably have the samediameter, and preferably rotate together and at the same rate. The outerdiameter of the permanent magnet stepper motor is approximately 12 mm to15 mm, and it is encased within a heat sink mount with built-intemperature sensing. The diameter of the narrow portions of the drum isapproximately 3 mm. The drum is supported at either end by rotary ballbearings 1111-1, 1111-2.

A filament or drive string 1110 passes through a hole 1113 in the drum'smandrel to go from the top drum 1108-T to the bottom drum 1108-B. Forexample, the midpoint of the string is knotted, and both ends of thestring pass through the hole 1113. After exiting the hole 1113, one endof string wraps around bottom drum and the other end wraps around topdrum. A knot 1115 anchors the string so the ends cannot be pulledthrough the hole 1113 and the drive string 1110 does not slip. Thesmallest dimension of the knot is larger than the diameter of the hole.The string has an outer diameter of 0.5 to 1 mm and is of a braidedconstruction, such that constituent strands are woven together, ishighly flexible, and is readily able to wrap about the small diameterdrum.

For the purposes of this description, the portion of the drive string1110 on the right of the drum (in FIG. 1A) is denoted 1110-R, and theportion of the drive string 1110 on the left of the drum 1108 (in FIG.1A) is denoted 1110-L. An end 1112-L of the drive string 1110 (of stringportion 1110-L) is attached to an outer structure 1103 which is mounted(e.g., with two screws) to the printed circuit board 1102. The outerstructure 1103 may be 3D printed, molded, or machined. The thickness ofthe printed circuit boards is generally in the range of 1 mm to 3 mm.The typical thickness of printed circuit board 1102 is approximately 1.5mm. The circuit board substrate material comprises fiberglass such asFR-4 or a carbon fiber reinforced composite.

As shown in FIG. 1B, an end 112-R of the drive string 1110 (110-R) maybe attached to a spring retaining part 1140 which is fitted into one endof the spring 1116 and housed by the spring retaining housing 1142. Thespring retaining part 1140 and housing 1142 may be 3D printed, molded,or machined parts. The thickness of circuit board 1104 is approximately2.5 mm and is relatively thick to provide increased stiffness. Thespring 1116 to which the string is attached preferably enables about5-10 mm of compression before bottoming out. The string is highlyinelastic, so the spring provides compliance when or if the grippermotor is driven into a hard stop during operation. In the absence of thespring compliance, the motor's gearbox would be subjected to relativelylarge forces upon impact. Such forces can potentially wear andultimately damage the teeth of the individual gears within the gearbox.In a particular example, the gearbox is a planetary gearbox with areduction ratio of about 100 to 1, wherein the individual gears areinjection molded plastic such as nylon, acetal, or PEEK.

The drum 1108 preferably has rounded flanges so that the drive string1110 does not wear and ultimately fail due to abrasion caused by thestring repeatedly rubbing on the drum flanges. The flanges have adiameter of about two times the minimum diameter along the length of themandrel. In one example, the minimum diameter is 3 mm and the flangediameter is about 6 mm. Reducing the minimum diameter increases themaximum tension that can be applied to the string.

The drive string 1110 is preferably a zero stretch, high strength,flexible drive string for efficient force transfer. A presentimplementation uses braided Vectran HT string with a diameter of 0.73mm. This drive string 1110 is, for example, a high-performancemultifilament spun yarn made of liquid crystal polymer (LCP). It hashigh strength and virtually no creep or elongation. The inventor hasfound that the Vectran string noted above has superior abrasionresistance, low creep, and excellent moisture resistance over a broadrange of temperatures. The string has 57 kg (˜125 pound) tensilestrength.

The gripper assembly 1100 is able to unplug any fiber connector fromamong an array of fiber connectors inserted along connector rows, thentransport that connector (as necessary), and then plug that fiberconnector into a connector plug. The direction of movement to plug orunplug fiber connectors is parallel to the long axis of rods 1120-1,1120-2.

The gripper assembly 1100 may include an engagement portion including asolenoid 1126 with a spring-loaded solenoid latch 1128 to engage with afiber optic connector. The latch is mechanically coupled to a rearconnector engagement element, the engagement element having an internallow friction ramp 1138 and latch blade 1128 (e.g., as shown in FIGS.5A-5B in which an elongated fiber optic connector 1500 engages with theengagement portion of 1122 in order to connect or disconnect opticalfiber 1502). The ramp features are important to the sliding action ofthe gripper when interacting with a connector and are detailed in FIG. 3and FIGS. 4A-4E. The solenoid 1126 is electrically actuated by anexternal controller to raise the latch 1128 as shown in FIG. 5A-5B sothat the fiber connector is able to be released from the gripper as thegripper pulls back and leaves the connector in its corresponding port.The latch 1128 is spring loaded with a compression spring 1129concentric with the moveable solenoid core 1131 so that the fiberconnector remained mechanically latched within the gripper even when thegripper is unenergized. The down or equivalently the “engaged” positionof the latch is detected with a miniature optical sensor 1310 thattransmits and detects light reflected off the latch 1128.

Winding the drive string 1110 on the rotating drum 1108 (by forwardoperation of the stepper motor 1106) pulls the outer structure 1103,riding on parallel rods 1120-1, 1120-2, to the right (in FIGS. 1A and1B), towards the structure 1105, by winding portions of drive string1110-L and unwinding portions of drive string 1110-R around the bottomdrum 1108-B and top drum 1108-T, respectively.

Alternatively, winding the drive string 1110 on the rotating drum 1108in the opposite direction (by reverse operation of the stepper motor1106) pulls the outer structure 1103, riding on parallel rods 1120-1,1120-2, to the left, away from the structure 1105, by unwinding portionsof drive string 1110-L and winding portions of drive string 1110-Raround the bottom drum 1108-B and top drum 1108-T, respectively. Thetotal travel distance from left to right of the outer structure is about20 mm. The winding drive string mechanism is able to generate a linearforce of over 20 Newtons when moving the outer structure 1103 in eitherdirection relative to the printed circuit board 1104 to which motor isattached.

The position of the slidable outer structure 1103 and potentially theoptical fiber connector 1500 engaged therein is sensed by a multiplicityof optical sensors (1302, 1304, 1306, 1308, 1310) attached to thecircuit board that are detected by controller electronics. The linearforce generated by the stepper motor is proportional to the drivecurrent output by the stepper motor driver electronics. The current isadjustable by the controller so that the linear force can vary from zeroup to 40 N.

By spring loading the drive string 1110, the string may remain taut andend-stop collisions may be avoided. The ideal spring constant isselected to enable the gripper to generate a plug-in force on connectorof about 10 N without fully compressing the compression spring. Thecompression spring serves as a soft bumper when the gripper reaches theend of travel, thereby guarding against motor and/or gearbox damage.

In a further example, FIG. 6A illustrates the multi-step process underthe control of a computer to unplug a fiber connector from an internalport within the NTM so that it can be moved and reconfigured and movedwithin the multiplicity of surrounding fibers with multiple processvalidation steps to ensure the successful completion of each step of theprocess.

With reference to the flowchart in FIG. 6A, the exemplary unpluggingprocess includes translating one connector row, so it is centrallyoffset from the others (at 1602). The process further includestranslating (at 1604) the gripper at the end of the robot arm in adirection normal to connector row substrate, to pass between connectortrack extensions onto a selected, programmably centered connector row.The process further includes (at 1606) monitoring the sensing element ofgripper. The process further includes (at 1608) detecting a change inthe state of the sensing element, which indicates that the gripper is inclose engagement with a target connector track element of the offsetconnector row. The process further includes (at 1610) stopping thetranslation of gripper upon the change in state. The process furtherincludes (at 1612) translating the gripper parallel to connector trackelement in a direction to engage the fiber optic connector. The processfurther includes (at 1614) stopping the translation when the grippersensing elements detect that the fiber optic connector is engaged withinthe gripper. The process further includes (at 1616) locking the fiberoptic connector within the gripper with a solenoid. The process furtherincludes (at 1618) translating the gripper parallel to connector trackelement and opposite the direction to unplug the fiber optic connector.The process further includes (at 1620) stopping the translation when thegripper sensing elements detect that the fiber optic connector issufficiently withdrawn to be clear of the connector receptacles, and (at1622) translating the gripper at the end of the robot arm in a directionnormal to the connector row substrate, to pass between connector trackextensions.

FIG. 6B illustrates the multi-step process under the control of acomputer to plug-in a fiber connector from an internal port within theNTM so that it can be moved and reconfigured and moved within themultiplicity of surrounding fibers with multiple process validationsteps to ensure the successful completion of each step of the process.

With reference to the flowchart in FIG. 6B, the exemplary plug-inprocess includes (at 1624) translating one connector row so it centrallyoffset from the others; (at 1626) translating the gripper with the fiberoptic connector therein at the end of the robot arm in a directionnormal to the common plane, to pass between connector track extensionsonto a selected, programmably centered connector row. The processfurther includes (at 1628) monitoring the sensing element of gripper;and (at 1630) detecting a change in state of a sensing element, whichindicates that the gripper is in close engagement with a targetconnector track element of the offset connector row. The process furtherincludes (at 1632) stopping the translation of gripper upon the changein state. The process further includes (at 1634) translating the gripperparallel to common plane in a direction to plug in the fiber opticconnector into connector receptacle, and (at 1636) stopping thetranslation when the gripper sensing elements detect that the fiberoptic connector is plugged into the connector receptacle. The processfurther includes (at 1638) unlocking the fiber optic connector withinthe gripper with a solenoid; and (at 1640) translating the gripperparallel to connector track element opposite the direction to plug inthe fiber optic connector. The process further includes (at 1642)stopping the translation when the gripper sensing elements detect thatgripper is sufficiently withdrawn to be clear of the fiber opticconnector; and (at 1644) translating the gripper at the end of the robotarm in a direction normal to the connector row, to pass betweenconnector track extensions.

The gripper has a finite service lifetime and is a consumable that canbe changed in the field. In a further example, to improve the fieldserviceability of the robotic cross-connect, it is advantageous for thegripper sub-system to be replaceable with minimal effort, skill, andlabor. A quick-connect mounting design between the removable grippersub-system and the robot arm subsystem is described below.

FIGS. 7A-7B illustrate a quick connect and disconnect mount to attachthe gripper assembly 1100 from the robot arm inner stage 1312 andprovide for easy installation, removal and replacement. This eliminatesthe need for tools or removeable fasteners, which is significant in thisapplication because it prevents the accidental release of tools orfasteners into the dense fiber cross-connect area where it is extremelydifficult to locate and retrieve such parts.

The quick connect and disconnect mount includes a combination of amulti-contact electrical interface 1316-1318 and a rigid, vibrationtolerant mechanical interface that does not require a tool to remove orlock the gripper into place. In a particular example, a femaleelectrical connector receptacle 1316 on a printed circuit board 1314 ismounted to the inner stage of robot arm 1312. A mating male electricalconnector receptacle 1318 is on the printed circuit board 1104 of thegripper assembly. The gripper 1100 is affixed and locked to the arm 1312by the quick release lock 1320. The quick release 1320, is, for example,a spring loaded knob which is pulled out to release the gripper.

ROBOT SUB-SYSTEM

The robot sub-system disclosed herein has unique design requirements toensure that fiber interconnections can be provisioned and reprovisionedover the lifetime of the system without interruption or faults, ondemand even after extended periods of inactivity. The service lifetimeis typically in excess of 10 years. Unique designs are required toeliminate the need for routine maintenance (e.g. lubrication, cleaning,etc.). This sub-system also must be easily replaceable without the needfor skilled labor.

A robotic assembly 2100 according to exemplary embodiments hereofcomprises a translatable, multi-stage telescopic robotic arm (FIG. 8)2102 on which a gripper assembly (not shown) may be positioned at theend of the arm. The robotic arm provides one axis of translation (i.e.“y direction”) in a two-axis robotic actuation system wherein the armtranslates in a direction orthogonal to the y direction (i.e. the “xdirection”), e.g. as shown in U.S. Pat. No. 10,345,526, the entirecontents of which are hereby fully incorporated herein by reference forall purposes). As described in U.S. Pat. No. 10,345,526, the robotic armis of a narrow width to allow it to descend into a dense fiber opticinterconnect volume with no mechanical interference and no contact withsurrounding fibers, and of extended depth to provide sufficient rigidityto experience minimal deflection under transverse forces includingconnector magnet repulsion and potentially oblique tension originatingfrom the fiber being carried in the gripper therein.

With reference again to FIG. 8, the robotic arm 2102 includes an outerstage 2108 and a rectangular hollow channel element 2104 (also referredto as the middle stage or C-channel) within which a linear and narrowerlower section or inner stage 2106 may move. The robotic arm 2102extension axis is in the y direction, and it may move in the orthogonalx direction. The gripper attached at the end of the inner stage is ableto translate incrementally in the z dimension.

The middle stage 2104 (the outer C-channel element) is preferablymanufactured from hardened, non-magnetic stainless steel (preferably 303or 304 stainless steel) to prevent corrosion. In a present exemplaryimplementation, the middle stage is 12.5 cm wide, 50 cm deep, and 75 cmlong. Preferably the wall thickness of the middle stage 2104 is 1.0 to1.5 mm.

The middle stage 2104 may move in the y dimension (i.e., in a verticaldirection) through the outer stage 2108, as illustrated in FIGS. 9A-9B.Accordingly, the middle stage 2104 may slide by rollers 2202-1, 2202-2,2202-3, 2202-4 (collectively and individually 2202) and spring-loadedrollers 2204 in the fixed outer stage 2108. The rollers 2202 arepreferably hardened and ground crowned rollers. The mounting mechanismmay also include a plurality of spring-loaded lubrication mechanisms2206-1, 2206-2 . . . 2206-x (collectively and individually springmechanism 2206) to maintain and/or control a position of the middlestage 2104 within the outer stage 2108 while still permitting smooth andcontrolled movement of the middle stage. The lubrication preventsgalling or wear of the stainless-steel components during long durationrolling contact with one another.

As detailed in FIG. 9B, an exemplary lubrication mechanism 2206 includesa lubrication element 2208 and a spring 2210 positioned in a hole 2212in the lubrication element 2208. The lubrication element 2208 and spring2210 are held in place against the upper stage by a housing 2214 screwedto the mounting mechanism. The lubrication element 208 may be, forexample, an machinable, oil-impregnated plastic element.

The use of oil-impregnated, spring loaded plastic lubrication elementsin which lubrication fluid slowly diffuses out on the time scale of 10years eliminates the need for maintenance over a 10-20 year lifetime ofa robot and extends the lifetime of the telescopic arm to greater thanone million cycles. The use of hardened and ground crowned rollerseliminates sharp edges that can degrade the C-Channel (middle stage2104) and eliminates wear and galling of the outer wall of theC-Channel. Galling (a form of wear caused by metallic adhesion betweensliding surfaces) is undesirable because it may lead to particulatesthat can contaminate the system and potentially collect on the delicatefiber connector end faces therein.

Spring loaded mounting of a subset of rollers to the outer stage has anumber of advantages, including providing preload to rollers so that theC-Channel or middle stage is tightly constrained and stable in angularposition while moving up and down. The preload force may be selected tobe sufficiently high (approximately 10-20 N) to maintain the C-Channel(middle stage 2104) in rigid, precise alignment, but not too high as tocause wear of the rollers and outer surfaces of the C-Channel.

Spring loaded mounting of a subset of rollers to the inner stage has anumber of advantages, including providing a slight preload to rollers sothat the inner stage is slightly compliant in angular position whilemoving up and down. The preload force may be selected to be limited(approximately <10 N) to provide compliance and to not cause wear of therollers on the inner surfaces of the C-Channel.

Example: Kinematic Robot Mounting/Leveling Mechanism

In a further example, to improve the field serviceability of the roboticcross-connect, it is advantageous for the robotic sub-system to bereplaceable with minimal effort, skill, and labor. A kinematic mountingdesign between the removable robot sub-system and the fixed fiberinterconnect system is described below.

The base of the robot has three distributed mounting locations near thecorners and edge of the robot baseplate, with initially adjustableheights and locations. The heights are determined and locked in place atthe time of initial factory alignment of the robot arm relative to theoutput connector columns. The mounting locations are next determined andlocked in place once the system is calibrated.

FIGS. 10A-10L depict aspects of a robot leveling mechanism according toexemplary embodiments hereof. This three-point kinematic mounting of therobot facilitates replacement and maintenance without requiring atedious realignment process. As shown in FIGS. 10A to 10D, a robotic armassembly 2300 (corresponding, e.g., to the robotic arm assembly 2100described above), may be connected to an inner door frame 2304 using arobot base plate 2306 and three (3) adjustable mounting/leveling screws2308-1, 2308-2, 2308-3.

A top plate 2310 of the inner door frame 2304 has three slotted holes2312-1, 2312-2, 2312-3, one for each of the screws 2308-1, 2308-2,2308-3. The combination of three screws and corresponding holes defineand provide a three-point leveling plane (as defined by the dashed linesA-A′, B-B′, and C-C′ in FIG. 10G). The position of the base plate 2306(and thus the robotic arm assembly 2300) relative to the top plate 2310of door (and thus relative to the inner door frame 2304) may be adjustedand configured in the directions of the arrows shown in FIG. 10H.

FIGS. 10H-10L shows aspects of the connection of the robot base plate2306 to the inner door frame 2304 with integral top plate 2310. Thedetail is shown for screw 2308-1, however it should be appreciated thatthe same approach is used for the other two screws. Screw 2308-1 has amachined slot to allow for flat-head screwdriver adjustment.

The screw has, for example a ¼″-20 thread. The screw is held in placewith a lock nut 2314 positioned over a washer 2316. A crownedhemispherical surface 2318 on the screw 2308-1 allows the base plate2306 to adjust in three dimensions axially to the other two adjustmentscrews without causing distortion of the base plate. A captive nut 2320is attached to the screw, and a nut 2322 prevents movement afteradjustment. Tightening these nuts does not distort the base plate 2306nor does it distort the door top plate 2310.

The robotic arm described above may be used, e.g., in a robotcross-connect system such as described in Telescent's U.S. Pat. No.10,345,526, the entire contents of which are hereby fully incorporatedherein by reference for all purposes. As described in U.S. Pat. No.10,345,526, a gripper attached to an end of a robotic arm is able tounplug any fiber connector from among an array of fiber connectorsinserted along connector rows, then transport connector and fiberattached thereto in a deterministic, optimal weaving pattern between thesurrounding fiber connectors of the array upon manipulation by a robotarm assembly.

Example: Horizontally Telescopic Robot Arm

In a further example, FIGS. 11A-11D schematically illustrate aspects ofan exemplary telescopic robot configured instead in a horizontalconfiguration. FIG. 11A shows the telescopic robot in a retracted state,whereas FIG. 11B shows it in an extended state. In this case, while theextension of the middle stage is actively driven by a motor coupled tothe middle stage by a timing belt, the extension of the inner stage inthe non-vertical direction does not have the assistance of gravity topull the inner stage downward while supported by the ribbon cabletraveling around the pulley at top of middle stage and fixed onto theouter stage.

Therefore, in this particular example, the inner stage is driven outwardtelescopically with the addition of a flexible drive element, such as abraided Vectran, Kevlar, or other flexible string or timing beltattached to the bottom of the inner stage, and wrapping around a pullyattached to the middle stage and then attached to the outer stage. Whenthe middle stage is driven by the motor/timing belt or lead screwsubassembly, motion will be transferred to the inner stage through theopposing combination of (1) the ribbon cable to retract in and (2) theflexible drive element to extend out.

In a specific example, the flexible drive element is a braided Vectrancord with a diameter of 0.5 to 3 mm. The pulley has an outer diameter ofabout 12 mm and spins on a rotary ball bearing. The Vectran cord isaffixed by a clamping means to the outer stage, wherein the clamp allowsthe cord to be affixed with the proper tension. Adequate tension or“preload” of this flexible drive element is necessary to minimizebacklash between when the ribbon cable retracts in the inner arm and theflexible drive element extends out the arm.

In a further fiber cross-connect system example illustrated in FIG. 11B,the robot arm is extendable horizontally and parallel to the 1D backbonewithin the fiber interconnect volume. This horizontal arrangement isadvantageous for height constrained applications of the system becausethe overhead associated with the robot arm does not contribute theoverall system height. This example further illustrates a small formfactor robotic cross-connect system that fits within an industrystandard 19″ data center rack.

This robot subsystem also utilizes the connector gripper, to unplug andplug-in fiber optic connectors to the internal connector panel. Thisrobot subsystem also interfaces to an internal cleaning cartridge, whichcleans the connector end face.

CLEANING CARTRIDGE SUB-SYSTEM

The cleaning cartridge sub-system disclosed herein ensures thatconsistently clean optical fiber end faces are maintained within thesealed cross-connect enclosure and over the lifetime of the system. Thecleaning process is based on a spool of commercially available cleaningfabric with the addition of actuation and sensing means to enable therobot to clean with high precision and repeatability. The cleaningcartridge sub-system is a consumable that can be quickly replaced whenthe fabric is exhausted.

With reference to FIGS. 12 and 13, a cleaning cartridge system 3100includes a top portion comprising a main housing 3102 operativelyconnected to a bottom portion having a bottom cover 3104. The topportion (in the main housing 3102) contains most of the operationalcomponents of the cleaning cartridge system 3100, whereas the bottomportion primarily contains the replaceable cleaning fabric and relatedcomponents.

As shown, e.g., in FIGS. 14A-14H, the top portion includes a gearmechanism, having a main drive gear 3306 engaged with an idler gear3308, which is engaged with a clutch gear 3310, and a clutch 3312. Theidler gear 3308 engages the main drive gear 3306 and the clutch gear3310. In operation, and as shown by the arrows in FIG. 14G, the maindrive gear 3306 rotates counter-clockwise, causing the idler gear 3308to rotate clockwise which causes the clutch gear 3310 to rotatecounter-clockwise. The gears are positioned on three gear shafts 3316,3318, 3320, and a top bearing plate 3314 aligns and secures the threegear shafts 3316, 3318, 3320 with perpendicularity to the main housing3102.

A one-way bearing 3322 (e.g., a one-way needle bearing) allows thegear/drive shaft 3316 to rotate only in the direction which advances thecleaning fabric. The bearing 3322 is positioned in a housing 3334 (seealso FIGS. 14K-14L), to hold the one-way bearing 3322. The bearing 3322is glued and pressed into the housing 3334, and the housing 3334 withthe bearing 3322 is positioned on the shaft 3316. The top bearing plate3314 holds the housing 3334 in place using, e.g., a screw 3336 in thehole 3338 in the housing. As configured, the bearing 3322 prevents thedrive shaft 3316 from clockwise rotation.

A linear actuator (LA) 3324 is connected to a lever arm 3326 by alinkage 3328. The linear actuator 3324 controls the precise advancementof the ribbon (as explained below) based on the displacement of thelever arm. The lever arm 3326 pivots by a certain amount to linearlyadvance the ribbon. In a presently preferred implementation, the leverarm 3326 pivots 31 degrees to linearly advance 1.5 mm of ribbon. Thoseof skill in the art will understand, upon reading this description, thatdifferent amounts of pivot of the lever arm 3326 will produce differentamounts of ribbon advancement. The ribbon advancement is selected suchthat the polished fiber optic connector ferrule tip, which is 1.25 mm indiameter for LC ferrules or 2.5 mm in diameter for SC ferrules, ispresented and cleaned on an unused portion of the fabric. The lever arm3326 may be positioned on a one-way bearing 3340 (see, e.g., the detailin FIGS. 14J-14K).

In a particular example, the linear actuator is a dc motor with anintegral lead screw to push or pull on its central member connected tothe linkage 3328.

A 360-count rotary encoder/counter 3330 may be used to confirmadvancement of the ribbon (to be described) and to determine when theribbon has been used up. Once the encoder shows no counts upon advancingthe fabric, this is the indicator that the ribbon is used up and thecontroller measuring the counts outputs an alarm indicating that thefabric must be replaced.

An electrical connector 3332 (e.g., a DB9 connector) provides aninterface to a printed circuit board (PCB) and/or other controlmechanisms (not shown). As noted, in present implementations thecleaning cartridge system 3100 is attached to a robot arm, and theelectrical connector 3332 may connect with the robot's interface board.

With reference to FIGS. 15A-15F, the lower section (inside bottom cover3104) contains a source cleaning fabric spool 3402 and a used cleaningfabric/take-up spool 3404. Both the source cleaning fabric spool 3402and the used cleaning fabric spool 3404 may be removed for replacement(e.g., when the source cleaning fabric spool 3402 is used up). Thecleaning fabric is preferably in the form of a 10-15 mm wide ribbon.

The take-up spool 3404 is connected to the drive shaft 3320 of theclutch gear 3310, whereby rotation of the clutch drive shaft 3320 causescorresponding rotation of the take-up spool 3404. Preferably the take-upspool 3404 secures to the clutch drive shaft 3320 with a left-handthread 3428 in order to prevent the spool from unscrewing/looseningduring operation.

The clutch 3312 serves two functions. First, it maintains at least aminimum tension on the ribbon/fabric 3500. Second, it allows slip tocompensate for re-wind overdrive between the take up spool 3404 and theclutch gear 3310. As the ribbon/fabric 3500 in consumed during cleaningprocess and wound onto the take-up spool 3404, the diameter of the spoolbecomes larger. Therefore, for a given fabric advance length (e.g. 1.5mm), this leads to a corresponding decrease in angular rotation of thespool as the fabric is consumed. The clutch 3312 provides slippageallows the advancement of the ribbon to always move at the designated1.5 mm linear length independent of the accumulated ribbon on thetake-up spool.

The cleaning ribbon/fabric 3500 passes from the source cleaning fabricspool 3402 to the take-up spool 3404 through a series of guide rollers3406, 3408, 3410. A drive roller 3412 with high friction/low sliprelative to fabric pulls the fabric from the source spool and winds usedfabric onto the take-up spool while maintaining alignment of the ribbonof cleaning fabric as it traverses the series of rollers.

The source spool 3402 may be connected to a shaft 3414. The shaft 3414may be connected to the rotary encoder/counter 3330. As shown, e.g., inFIGS. 15C-15D, a stainless-steel washer 3416 may be permanently fixed tothe main housing 3102. A gasket 3418 (for compression) is positioned onthe shaft 3414 between the washer 3416 and a correspondingstainless-steel washer 3420 permanently fixed to compression brake rotor3422. With reference to FIG. 15C, a disk wave spring washer 3426 mayapply consistent force to the compression brake rotor 3422.

As shown in FIG. 16, a close out shield 3424 protects clean unwoundfabric 3500 (on spool 3402) from contamination.

Mounting screws 3502, 3504 may be used to attach the cleaning cartridgesystem 3100 to a robot undercarriage (e.g., the underside of a robotmodule) so that the robot arm passes centrally through the cleaningcartridge and the gripper can be positioned within the cleaningcartridge so that the gripper pushes the fiber connector end face intothe cleaning fabric and the gripper is then translated a distanceperpendicular to the fabric feed direction to clean the fiber end face.This distance is typically 4 to 10 mm, less than the 14 mm width of thecleaning fabric.

The guide rollers 3406, 3408, 3410 guide and position the ribbon/fabric3500 as it passed across a pressure sensing pad and mounting assembly3600.

With reference to FIGS. 17A-17B, the pressure sensing pad and mountingassembly 3600 includes a pressure sensor 3602 covered by a rubber pad3604, permanently glued to cover the pressure sensor 3602. The pressuresensor is, for example, a resistive force gauge whose electricalresistance is a sensitive function of mechanical pressure at the centralregion of the sensor.

The guide rollers 3406, 3408, 3410, help to keep the fabric 3500 alignedas it moves through the designated cleaning area 3606 (FIGS. 15A-15F).

The fabric 3500 passes in front the pressure sensor (pad 3604).

In presently preferred operations, the cleaning cartridge system 3100 isattached in a fixed position relative to robot carriage, surrounding therobot arm that traverses columns of spaced-apart connectors (e.g., asdescribed in U.S. Pat. No. 8,068,715).

The cleaning cartridge system 3100 must be small enough to allow it tobe installed in the limited volume beneath the robot carriage.

In operation, an end of an optical fiber (that is to be cleaned) isbrought into contact with the pressure sensor 3602 (in the designatedcleaning area 3606). The pressure sensor triggers the gripper motor tostop advancing the ferrule once it makes contact with the fabric andensures that the pressure is within suitable upper and lower bounds soas to not tear fabric, not wear out compliant pad behind fabric, and notdamage optical fiber end face. With sufficient pressure to trigger thesensor, after a time delay the fabric 3500 advances. The gripper thenmoves the fiber connector end face transverse to the feed direction ofthe cleaning fabric over a distance of 4 to 10 mm to “swipe” and therebyclean the end face.

In a further example, the cleaning of the end face is further confirmedby an end face inspection microscope device, which analyzes the image todetermine if cleaned end face passes predefined metrics for the numberand size of contaminants and or defects in the vicinity of the opticalfiber core.

In a further example, the cleaning of the end face is confirmed by anoptical time domain reflectometer or OTDR, which sends light pulsesthrough the fiber and connector to measure the insertion loss and returnloss resulting when the fiber connector end face is plugged into amating connector by, for example, a robotic arm and gripper.

Exemplary operation of the cleaning cartridge system 3100 is shown inthe flowchart 3700 of FIG. 18. First, at 3702, the gripper (on the endof a robot arm, not shown) engages the fiber connector tip with thecleaning fabric 3500 and activates the resistive touch sensor (pressuresensor (pad 3604)). A voltage change across the touch sensor triggers atime delay circuit #1 (at 3704). Next, the robot arm moves the gripperup vertically to swipe the fiber connector tip across the cleaningfabric (at 3706) in a direction perpendicular to the direction in whichthe fabric advances over a distance of 2 to 10 mm. After a delay #1(e.g., 3-4 seconds), time delay circuit #2 triggers and switches ondrive current to linear actuator in one direction (actuator 3324 movesoutward) for, say, 2.5 seconds (at 3708). At the end of time delay #2the time delay circuit #3 will start, which will switch the linearactuator's moving direction (actuator 3324 moves inward). During thismove the drives lever arm 3326 rotates drive shaft through opposingone-way needle bearings (at 3710).

Rotation of drive shaft 3320 rotates fabric friction feed roller (at3712). The fabric 3500 is advanced by, e.g., 1.5 to 3 mm (at 3714) suchthat a new clean portion of fabric is presented for subsequent cleaningprocess. The circuit is then reset (at 3716) and ready for next cleaningcycle. With the settings described above, about 7,000 to 9,000 cleaningscan be performed for a spool with 11 to 13 meters of cleaning fabric.

The optical encoder 3330 may monitor each fabric advance in order toestimate the remaining cleaning fabric length on the spool 3402, andthereby to indicate a finished cleaning fabric roll. The encoder pulsesare counted and stored by an external controller, such that theremaining cleaning capacity is monitored and reported. The cleaningcartridge system 3100 described thereby provides consistent fabricadvance.

In a further example, the method of cleaning the optical fiber end facewith a cleaning fabric in an automated cross-connect system thatreconfigures optical fiber end faces among a multiplicity of receivingreceptacles, comprises of the steps of (1) energizing an electricalactuator, (2) rotating a fabric advance roller to translate fabricribbon, (3) unspooling fabric ribbon partially from fabric ribbon sourcespool, (4) advancing a pre-determined section of fabric to present anunused section of fiber at cleaning element, (5) counting the encoderpulses generated when advancing the fabric, (6) waiting for the fabricadvance to complete based on the encoder pulse count, (7) contacting thefiber end face substantially normal to the fabric surface, (8) detectingthe contact of fiber end face on fabric using a force or pressuresensor, (9) swiping the fiber end face in a direction substantiallynormal to fabric ribbon length, (10) withdrawing the cleaned fiber endface from cleaning element, and plugging the fiber end face into one ofthe receiving receptacles.

In a further example, this is followed by the additional step ofmeasuring the backreflection of the cleaned fiber end face to verifycleaning. If the backreflection of the cleaned fiber end face exceeds agiven threshold, all steps in the process are repeated. Typicalbackreflection thresholds are not to exceed −50 dB. The backreflectioncan be measured, for example, by an optical time domain reflectometer(OTDR) or optical coherence domain reflectometer (OCDR).

A fiber end face may be inspected for cleanliness using an opticalmicroscope and image processing system may be used to identifycontamination. If the image processing system determines that the fiberend face is not adequately cleaned, all steps in the above process maybe repeated.

FIBER OPTIC TENSIONING REEL SUB-SYSTEM

The fiber optic tensioning reel sub-system disclosed herein has uniquedesign requirements to ensure that fiber interconnections can beprovisioned and reprovisioned over the lifetime of the system withoutinterruption or faults, on demand even after extended periods ofinactivity. The service lifetime is typically in excess of 10 years.Consistency of fiber tensioning under all possible configurationsrequires significant technical advances. The fiber optic sub-system mustbe easily replaceable without the need for skilled labor.

With reference to FIG. 19, a reel assembly 4010 comprises a cable spool4012 rotatable about a screw 4014 with a central axis concentric withrotary bearing 4016. The cable spool has a cable winding support annulus4018 concentric with a central axis X-X′ defined by the axis of thescrew 4014 passing through the center of rotary bearing 4016. A spacer4015 may be provided between the screw 4014 and the cable spool. Thecable spool 4012 has an annular surface 4020 attached to disk 4022 forwinding optical fiber cable thereon.

The surface of disk 4022 preferably has a flatness of less than 0.005″(0.127 mm) and the annular surface 4020 has a radius of curvature atleast greater than a minimum bending radius of the optical fiber cable4024 that is repeatedly wound and unwound thereon. The typical outerdiameter of annular surface 4020 is 95 mm to 100 mm.

A central portion of the continuous length of optical fiber passesthrough a tube 4026 with rectangular cross-section, the tube preferablycomprises a dual-lumen tube with two parallel, spaced apart lumen, thefirst lumen containing therein an optical fiber and the second lumencontaining an internal wire 4027 (e.g., plano or stainless steel springwire) element. (See, e.g., FIGS. 7C and 7D of U.S. Pat. No. 10,042,122).The nominal outer dimensions of the dual lumen tube are 2.4 mm×0.89 mm,and the diameter of the lumens is about 0.5 mm.

The dual lumen tube is preferably made of a flexible polymer with lowcoefficient of friction and the polymer material may exhibit a lowmodulus and low stiffness relative to an internal wire element. The duallumen tube is bonded at one end to a slot or channel 4028 on the bottomside of disk 4022, so that a middle portion of the optical fiber followsa path from the bottom side of disk 4022 to the top side, through anopening 4030 connecting the top and bottom sides of the disk 4022.

A heat shrink tube 4029 may be positioned to increase the outerdimensions of the dual lumen tube and so to serve as an anchor,preventing the dual lumen tube from getting pulled into the reel duringprocessing, before it is finally fixed in place (e.g., with a clip andglue).

The internal wire element is straight (not coiled) in its free state andmay act as a stiffening element which maintains a radius of curvature ofthe fiber at least greater than a minimum bend radius of the opticalfiber throughout the range of rotation angles of the disk 4022. Theportion of the optical fiber in the tube can potentially move (e.g.,piston or longitudinally slide) freely within the tube's lumen as needed(e.g., when the fiber is retracted or extended from the reel assembly).

The optical fiber with an acrylate coating having an outer diameter of0.125 to 0.250 mm diameter may further have a protective, wearresistant, low friction jacket of 0.5 to 0.9 mm outer diameter, thejacket fabricated of Hytrel® TPC-ET thermoplastic elastomer, PEEK or afluoropolymer such as PFA, ETFE, or PTFE (Teflon).

The optical fiber cable 4024 is continuous with polished fiber opticconnectors 4050-1, 4050-2 at opposite ends, and kept at a radius ofcurvature in excess of an established minimum at all locations along itslength. The minimum bend radius of optical fiber ranges from 5 mm to 25mm, depending on the manufacturer and design.

A mandrel 4020 of soft rubber may be positioned between the cable spool4012 and a cover disk 4032. As the optical fiber under tension iswrapped onto the spool, it contacts the soft mandrel 4020 along theinner diameter of the spool, to protect the optical fiber 4024 andeliminate fiber optic microbending, macrobending and associatedinsertion loss. The cover disk 4032 outer perimeter is circular, withopen sectors 4033 along its perimeter, and is molded using a plasticmaterial having with a highly light reflecting surface. The open sectors4033 enable an optical sensor 4040 on printed circuit board 4046positioned in vicinity of the perimeter to detect the rotation of thereel, since as the disk rotates the open sectors 4033 will pass by thesensors and the lack of light reflecting from the open sectors 4033 isdetected electronically.

In a particular example, twelve reels are arranged on the surface of thesubstrate and six separate circuit board assemblies 4046 with reflectiveoptical sensors 4040 are used to detect the individual rotations of thetwelve reels. The sensors are positioned at a distance of 0.5 to 1 mmfrom the outer reflective surface of the cover disk 4032.

A cover piece 4034 may be positioned to retain the power spring 4036 sothat it does not expand unstably out of the plane containing the powerspring. The cover piece 4034 is attached/bonded to disk surface 4022.

The rotatable end of a prestressed flattened power spring 4036 isconnected to the cover piece 4034 (e.g. using an end 4038 of the spring4036 at location 4048 on the cover piece 4034, FIG. 21). Thenon-rotatable end of power spring 4036 is attached to a central (orpower spring) mandrel 4042 that is fixed by a screw 4014 and threadinsert 4044 so that it does not rotate. The prestressed, flatteneddesign for power spring 4036 is used to minimize torque variation asfiber is pulled off the reel and concurrently as the power spring iswound tighter. The flattened power spring 4036 reduces variation intension of the fiber as it is retracted and/or extended.

A die cut ring 4052 of UEMW film with pressure sensitive adhesive on oneside (visible in FIG. 22) adheres to the surface of disk 4022. Beneaththis die cut ring, the optical fiber originating from the dual lumentube below the disk 4022 and exiting the top of the disk 4022 follows aspiral path towards the outer diameter of the disk 4022. The fiber alongthis spiral path passes under the rubber O-ring 4020 with squarecross-section, and then wraps about the outer diameter of the annulusand the far end exits the reel and it directed towards the centralone-dimensional backbone.

A multiplicity of reel assemblies 4010 may be mounted onto aTeflon-coated sheet metal tray 4060 (FIG. 22), wherein the Tefloncoating minimizes friction as the spiral element winds and un-winds. Themetal tray 4060 may hold multiple reel assemblies. For example, in animplementation, a metal tray holds twelve (12) reel assemblies 4010 asdescribed above. Another implementation has eighteen (18) reelassemblies 4010 on a metal tray.

As shown in FIGS. 20A-20C, each real assembly includes a helically woundlength of dual lumen tube. The length ranges from 152 cm to 280 cm, witha typical length of about 183 cm. The dual lumen tube may include afriction reducing chemical additive such as PTFE to enable it to coiland uncoil with minimal friction and minimize hysteresis of resultingreel torque/fiber tension. The base material of the dual lumen tube isfabricated of PEBAX, PEEK, nylon, or a fluoropolymer, for example. Ifthe diameter of spring wire within the dual lumen tube is too large thenthe friction between turns of the spiral dual lumen tube increases,which produces excessive hysteresis in fiber tension (e.g. greater than85 gm of hysteresis in fiber tension) as the optical fiber is retractedvs extended.

As the diameter of spring wire is decreased, the torque and hysteresisof torque is decreased. The hysteresis is about 85 gm for a diameter ofspring wire of 0.45 mm and length of 259 cm, 57 gm for a diameter ofspring wire of 0.45 mm and length of 183 cm, 42.5 gm for diameter ofspring wire of 0.41 mm and length of 183 cm, and 28 gm for diameter ofspring wire of 0.36 mm and length of 183 cm. The spring wire isfabricated of straightened spring tempered stainless steel, for example17-7 or 300 series stainless.

FIBER OPTIC TENSIONING PULLEY SUB-SYSTEM

The fiber optic tensioning pulley sub-system disclosed herein has uniquedesign requirements to ensure that fiber interconnections can beprovisioned and reprovisioned over the lifetime of the system withoutinterruption or faults, on demand even after extended periods ofinactivity. The service lifetime is typically in excess of 10 years. Thefiber optic sub-system must be easily replaceable without the need forskilled labor. Consistency of fiber tensioning under all possibleconfigurations and in a compact form factor requires significanttechnical advances.

With reference to FIGS. 23A-23B, a three-dimensional array of pulleysarranged on a substrate 5002 with a fixed set of pulleys 5004 and amoving set of pulleys 5006 on a spring loaded, moveable sled 5008 and anoptical fiber cable 5010 repeatedly wound therebetween is disclosed. Thesystem comprises a flat substrate, about 425 mm by 375 mm and 0.6 mmthick, with a common central fiber backbone 5012 with a stacked lineararray of low friction fiber cylindrical guides 5014, each with an outerdiameter (OD) of 1 mm, inner diameter (ID) of 0.75 mm, and a length ofabout 75 mm. A multiplicity (e.g. twelve) of optical fiber cables withouter diameters of 0.4 mm and length of 3 m and with connectors 5016 atboth ends, pass through a corresponding number of fiber guides. Each ofthese fibers have a corresponding spring-loaded pulley system 5018 whichstores up to a maximum length (e.g. 1.5 m) of optical fiber cable andproduces a precise tension.

Each pulley subsystem 5018 associated with a single fiber cablecomprises a moveable sled comprised of several pulleys 5006 rotatingwith outer diameters of about 20 mm on a common shaft 5020 with adiameter of about 1.5 mm and with a low coefficient of friction slidingelement. A pair of contact force spring 5022 extendable ends areattached to one end of the sled, and the fixed ends of the constantforce springs are each within a circular housing 5024 that is free torotate about a fixed shaft 5026 attached to the substrate. Opposite thecircular housing, at a distance of about 250 mm, are the fixed set ofpulleys 5004. Each optical fiber cable repeated wraps around fixed andmoveable pulleys.

Starting from the fixed connector end 5016-1 of the fiber optic cable,which is attached to a connector patch-panel 5028, the cable is routedto a fixed clamp 5030 attached to the substrate. From the clamp, thecable wraps 180 degrees around a first pulley 5006-1 of the sled, thenwraps 180 degrees around a first fixed pulley 5004-1, then wraps 180degrees around a second pulley 5006-2 of the sled, then wraps 180degrees around a second fixed pulley 5004-2, then wraps 180 degreesaround a third pulley 5006-3 of the sled, then wraps 180 degrees arounda third fixed pulley 5004-3, then wraps 180 degrees around a fourthpulley 5006-4 of the sled, then wraps about 90 degrees around a fourthfixed pulley 5004-4 with integral encoder wheel 5032. After this fourthfixed pulley, the fiber cable is routed by one of the redirectingpulleys 5034 to one of the multiplicity of backbone guides.

These elongated fiber cable and pulley sub-systems 5018 are repeatedacross the substrate in a 1×12 array. Each tray thus includes an arraywith 4 levels of pulleys arrayed across 12 positions.

The rotation of each encoder wheel attached to each fourth fixed pullyis detected by a reflective photo-interrupter device 5036 comprising anLED light source and phototransistor on a printed circuit board (PCB)substrate 5038 that further interfaces to a controller and logic board(not shown in this diagram). To monitor the potentially changeablelength of optical fiber extended and/or retracted by the pulley system,an electronic encoder subsystem is utilized. In this particular example,the reflective photo-interrupter is used to detect the rotation of oneof the optical fiber pulleys. To prevent fiber slippage on this pulley,a compliant, high friction surface on the pulley mandrel is desirable.Moreover, the printed, reflective encoder wheel is attached to one ofthe pulleys and the reflective photo-interrupter is precisely positionedin vicinity of reflective encoder wheel.

Unlike a typical block and tackle winch arrangement to lift loads, inthis case each pulley subsystem 5018 divides the force F_(spring)generated by one or more extension springs by an integer value ofMechanical Advantage (MA) to transfer a repeatable and substantiallyconstant Tension T_(fiber) on an optical fiber cable subsystem 5010. Forthe example illustrated in FIGS. 23A-23B, there are 8 fiber segmentsbetween the fixed and moveable pulleys. Therefore,MA=F_(spring)/T_(fiber)=number of segments of optical fiber=8. Thedecreased tension force produced by the spring(s) is offset by both theincreased length of optical fiber retained by the slack buffering system5018. There are also force losses that further decrease the tension,primarily from the friction of the pulleys on their shafts and thetorque required to overcome the rotational inertia of the pulleys.

The tension on the optical fiber cable subsystem 5018 is generated by ahelical wound constant force spring 5022. It is a pre-stressed flatstrip of spring material which is formed into virtually constant radiuscoils around itself or on a drum. When the strip is extended (deflected)the inherent stress resists the loading force, the same as a commonextension spring, but at a nearly constant (zero) rate. A constanttorque is obtained when the outer end of the spring is attached toanother spool and caused to wind in either the reverse or same directionas it is originally wound. The full rated load of the spring is reachedafter being deflected to a length equal to 1.25 times its diameter.Thereafter, it maintains a relatively constant force regardless ofextension length. The load is basically determined by the thickness andwidth of the material and the diameter of the coil.

A constant force spring is usually mounted by first tightly wrapping iton the circular drum 5024, then extending and attaching the free end tothe sled. The strip becomes unstable at long extensions and should beguided to prevent twisting or kinking on recoil. For example, as shownherein the constant force springs are mounted back to back in parallel,which provides mechanical rigidity transverse to the extension axis.

Each subsystem 5018 comprises a pair of blocks, each block with 4pulleys, one block fixed, and the other block attached to a pair ofextension constant force springs. The tension of the optical fiber cableis reduced by 8 from the total force provided by the power spring(s),corresponding to the number of fibers segments between the fixed blockof pulleys subsystem 5004 and the moveable, spring-loaded blocksubsystem 5006. The radius of curvature of the optical fiber cableshould be maintained at a level greater than 5 mm for bend insensitivefiber, so that the optical insertion loss caused by the bends remainlow; that is, less than about 0.1 dB.

When extending or retracting the optical fiber, the fiber experiencestension that results from the reduced force of the constant forcespring, the frictional force of the pulleys, and the torque required toovercome the rotational inertia of the pulleys. The frictional componentresulting from the pulleys is based on the ratio of pulley mandreldiameter to central shaft diameter. It is optimal from the standpoint ofreducing friction to minimize central shaft diameter. The tray includesadditional guidance pulleys to redirect fiber with low friction.

In a particular example, the tension is generated by constant forcespring(s) 5022 attached to the sled with moveable pulleys. The keyparameters of the constant force spring are:

-   -   Extended length=0.46 m    -   Load=16 gm-f    -   Thickness=0.125 mm    -   Width=8 mm    -   ID=17.5 mm    -   OD=20 mm    -   Material: 301 Stainless Steel

In a particular example as illustrated in FIGS. 24 and 25, the system offiber optic cable length buffers auto-tensions optical fiber cables,each fiber cable with distal and proximal ends and extendable from thelength buffer. Typically, both distal and proximal ends have connectors,but in some applications only the distal end has a connector and theproximal end is available to fusion splice into the fiber optic network.The robot reconfigures the distal end of connector within the array ofconnector receptacles, and if the proximal ends are connectorized, theyare plugged into the patch-panel segment of the corresponding tray.

In a further example, the tray is comprised of a central, stacked lineararray of flexible, low friction through guides attached to substrate,and a multiplicity of the length buffers arrayed on the substrate,wherein the length buffers each include a spring-loaded moving sled witha multiplicity of freely rotating pulleys on a moving common shaft, anda spaced-apart fixed common shaft with an equal multiplicity of freelyrotating pulleys thereon, wherein the fiber optic cable wraps in arepeated circuit around opposing sets of pulleys on the moving shaft andon the fixed shaft and is routed through one of the low friction throughguides to a fiber optic connector at the distal fiber end.

Multiple identical trays can be stacked on top of one another within acommon housing, to produce modules with a number of cables in multiplesof 12. Moreover, multiple modules can be stacked on top of one anotherin an enclosure to further increase the number of trays and cableswithin the cross-connect system.

The length of fiber extendable from the buffers is approximately equalto the number of circuits multiplied by the maximum distance between themoving and fixed common shaft. The spring-loaded moving sled is attachedto a pair of power springs at one end and attached to the substrate atthe other end and extending in opposition from their fixed housing. Theaverage tension of the fiber optic cable is equal to the totalretraction force of the spring pair divided by the number of circuits.

The length and tension are selected so that the robotic module is ableto translate any of the distal connectors between any arbitrary pair ofmating receptacles without subjecting the optical fiber cable toexcessive tensile and shear forces.

In a further example, a fiber optic cable length buffer device thatauto-tensions a moveable end of an optical fiber cable that isextendable from the length buffer and opposite a fixed end of theoptical fiber cable, wherein the length buffer is comprised of aspring-loading translating sled with a multiplicity of freely rotatingpulleys about a common first shaft affixed to the sled; a spaced-apartfixed common second shaft with an equal multiplicity of freely rotatingpulleys thereon; wherein the fiber optic cable wraps in a repeatedcircuit around opposite pairs of pulleys on the first shaft and on thesecond shaft, and the moveable end of fiber optic cable is routedthrough the low friction through guide to a fiber optic connector, theforce produced by spring-loading on sled equal to an integer multiple ofthe tension force imparted on the moveable end of the optical fibercable, wherein the ratio of the pully outer diameter to the shaft outerdiameter is about 10 to 1 to minimize friction of the pullies on shafts,wherein the tension force imparted on the moveable end of the opticalfiber cable is typically in the range of 20 to 60 gm-f.

As shown in the process flow chart in FIG. 26, the method of maintainingprecise tension of optical fiber cables extendable from arrayed spoolscomprises of the steps of (1) extending one of the optical fiber cablesfrom the arrayed spools by robot actuator, (2) sliding one of theoptical fiber cables through one of an array of flexible guides, (3)rotating a roller attached to a rotary encoder to generate encoderpulses, (4) counting the encoder pulses, (5) pulling the optical fiberscable wrapped around spools in multiple circuits on a sled travelingbetween two endpoints, (6) rotating the one or more arrayed spools onthe sled with different rotation speeds, (7) translating a sled along astraight path due dynamic extension force of optical fiber cableswrapped around spools of sled, (8) pulling one or more springs attachedat one end to the sled from their housing to impart a restoring forcethat maintains the precise tension.

The precise tension is in the range of 10-30 gm-f and increases to 40-75gm-f as the length of optical fiber cable extended increases to about 1m. The number of encoder pulses is compared to the calculated extensionlength to verify that the fiber optic cable is properly extended orretracted. The robot actuator is driven so that the travel of the sledis a fraction of the travel of the robot actuator.

ROBOTIC CROSS-CONNECT SYSTEM

In accordance with aspects hereof, unique robotic cross-connects systems(FIG. 27) are achieved by incorporating a controller sub-system 6001executing instructions according to the KBS algorithm (e.g., asdescribed in U.S. Pat. No. 8,068,715) to a robot subsystem 6002 with atranslatable platform carrying a telescopic robot arm with a grippersub-system 6003 attached to end of arm and a cleaning cartridgesubsystem 6007 attached to translatable platform, and a multiplicity offibers with connectors that are carried by the gripper, each fiberindependently tensioned and retracted within an arrayed storage andtensioning sub system 6004 incorporating a multiplicity of springpowered retractors. The telescopic arm may be a multi-stage unit with anouter stage attached to translatable platform, a middle stagetranslating within the outer stage and an inner stage sliding within themiddle stage and with a gripper attached at one end. The extension axisof the telescopic arm may be parallel to the direction of theone-dimensional backbone of flexible, low friction fiber guides, and isperpendicular to translatable connector rows that independentlytranslate according to the KBS algorithm. The extension axis of thetelescopic arm can be oriented vertically or horizontally, depending onspace constraints and the number of fibers with connectors.

An array of spring powered retractors are comprised of a stackedmultiplicity of one or both of spring-powered reel assembly trays orspring-powered roller assembly trays that tension and store excesslengths of continuous optical fiber cables with one or more connectorsat their ends.

The controller sub-system 6001 may be, for example, based on Linuxservers with Ethernet interfaces to communicate with the sub-systems.The controller may be in bi-directional electronic communication withsub-systems such as those illustrated in FIG. 27 to execute a sequenceof mechanical moves and electronic sensing, in a temporal relationshipthat ensures proper operation of each sub-system by validating theproper execution of each move before continuing on to the next step inthe process. The multi-step reconfiguration process may take at least 30seconds per port to complete.

The controller sub-system 6001 may be further in communication with anoptical power monitor (OPM) sub-system 6006 to measure insertion lossand optical power of the cross-connect. OPMs use photodiodes, amplifiersand analog to digital conversion and look-up tables to measure theoptical power within optical fiber cables.

The controller sub-system 6001 may be further in communication with anoptical time domain reflectometer (OTDR) sub-system 6005 to measureinsertion loss, backreflection and length of each cross-connect andcables attached thereto. Suitable OTDRs are commercially available fromsuppliers such as Exfo, Viavi, Anritsu and ADVA.

The controller sub-system 6001 may be further in communication with afiber end face inspection microscope sub-system 6008 to measure orevaluate the cleanliness of the fiber endface. Suitable inspectionmicroscope sub-systems are commercially available from suppliers such asViavi, Sumix, AFL, etc.

Cross-connect systems and subsystems as disclosed may be used toautomate data centers and networks. This application requires a veryhigh level of reliability and features that eliminate the interruptionof transmission through the fiber optic cables under any conceivablefaults. Accordingly, the cross-connect system disclosed herein isdesigned such that any of the above-mentioned sub-systems as shown inFIG. 27 can be removed and replaced, without interrupting thetransmission of signals through the system. The time to replace anysub-system is typically less than 60 minutes and requires minimalexperience to perform the replacement. These features are essential toensure high availability of the system and automation services enabledby the system.

CONCLUSION

Where a process is described herein, those of ordinary skill in the artwill appreciate that the process may operate without any userintervention. In another embodiment, the process includes some humanintervention (e.g., a step is performed by or with the assistance of ahuman).

As used herein, including in the claims, the phrase “at least some”means “one or more,” and includes the case of only one. Thus, e.g., thephrase “at least some ABCs” means “one or more ABCs” and includes thecase of only one ABC.

As used herein, including in the claims, term “at least one” should beunderstood as meaning “one or more,” and therefore includes bothembodiments that include one or multiple components. Furthermore,dependent claims that refer to independent claims that describe featureswith “at least one” have the same meaning, both when the feature isreferred to as “the” and “the at least one.”

As used in this description, the term “portion” means some or all. So,for example, “A portion of X” may include some of “X” or all of “X.” Inthe context of a conversation, the term “portion” means some or all ofthe conversation.

As used herein, including in the claims, the phrase “using” means “usingat least,” and is not exclusive. Thus, e.g., the phrase “using X” means“using at least X.”

Unless specifically stated by use of the word “only,” the phrase “usingX” does not mean “using only X.”

As used herein, including in the claims, the phrase “based on” means“based in part on” or “based, at least in part, on,” and is notexclusive. Thus, e.g., the phrase “based on factor X” means “based inpart on factor X” or “based, at least in part, on factor X.”

Unless specifically stated by use of the word “only,” the phrase “basedon X” does not mean “based only on X.”

In general, as used herein, including in the claims, unless the word“only” is specifically used in a phrase, it should not be read into thatphrase.

As used herein, including in the claims, the phrase “distinct” means “atleast partially distinct.” Unless specifically stated, distinct does notmean fully distinct. Thus, e.g., the phrase, “X is distinct from Y”means that “X is at least partially distinct from Y,” and does not meanthat “X is fully distinct from Y.” Thus, as used herein, including inthe claims, the phrase “X is distinct from Y” means that X differs fromY in at least some way.

It should be appreciated that the words “first,” “second,” and so on, inthe description and claims, are used to distinguish or identify, and notto show a serial or numerical limitation. Similarly, letter labels(e.g., “(A)”, “(B)”, “(C)”, and so on, or “(a)”, “(b)”, and so on)and/or numbers (e.g., “(i)”, “(ii)”, and so on) are used to assist inreadability and to help distinguish and/or identify, and are notintended to be otherwise limiting or to impose or imply any serial ornumerical limitations or orderings. Similarly, words such as“particular,” “specific,” “certain,” and “given,” in the description andclaims, if used, are to distinguish or identify, and are not intended tobe otherwise limiting.

As used herein, including in the claims, the terms “multiple” and“plurality” mean “two or more,” and include the case of “two.” Thus,e.g., the phrase “multiple ABCs,” means “two or more ABCs,” and includes“two ABCs.” Similarly, e.g., the phrase “multiple PQRs,” means “two ormore PQRs,” and includes “two PQRs.”

The present invention also covers the exact terms, features, values andranges, etc. in case these terms, features, values and ranges etc. areused in conjunction with terms such as about, around, generally,substantially, essentially, at least etc. (i.e., “about 3” or“approximately 3” shall also cover exactly 3 or “substantially constant”shall also cover exactly constant).

As used herein, including in the claims, singular forms of terms are tobe construed as also including the plural form and vice versa, unlessthe context indicates otherwise. Thus, it should be noted that as usedherein, the singular forms “a,” “an,” and “the” include pluralreferences unless the context clearly dictates otherwise.

Throughout the description and claims, the terms “comprise,”“including”, “having”, and “contain” and their variations should beunderstood as meaning “including but not limited to”, and are notintended to exclude other components unless specifically so stated.

It will be appreciated that variations to the embodiments of theinvention can be made while still falling within the scope of theinvention. Alternative features serving the same, equivalent, or similarpurpose can replace features disclosed in the specification, unlessstated otherwise. Thus, unless stated otherwise, each feature disclosedrepresents one example of a generic series of equivalent or similarfeatures.

The present invention also covers the exact terms, features, values andranges, etc. in case these terms, features, values and ranges etc. areused in conjunction with terms such as about, around, generally,substantially, essentially, at least etc. (i.e., “about 3” shall alsocover exactly 3 or “substantially constant” shall also cover exactlyconstant).

Use of exemplary language, such as “for instance”, “such as”, “forexample” (“e.g.,”) and the like, is merely intended to better illustratethe invention and does not indicate a limitation on the scope of theinvention unless specifically so claimed.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiment, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

Appendix: Abstracts

The following are Non-Limiting Abstracts for Various DisclosedEmbodiments. Gripper Sub-System

In a fiber optic cross-connect in which a robot selectively transportsfiber optic connectors between different positions, a fiber opticconnector gripper assembly, connectable to said robot, the gripperassembly comprising: a stepper motor drive, responsive to commandsignals and mounted on a support structure; a dual drum connected to thestepper motor drive and rotatable about a first axis, said dual drumcomprising a top drum portion and a bottom drum portion; a plurality ofbearing shafts slidably engaged in spaced apart relation in the supportstructure along axes perpendicular to the first axis; a pair of spacedapart terminal blocks fixedly mounted on opposite ends of the bearingshafts; and a length of drive string connected to the dual drum. A firstportion of said drive string is positioned to wind about the bottom drumportion when the drum is rotated, and wherein an end of said firstportion of said drive string is connected to a first of said terminalblocks. A second portion of said drive string is positioned to windabout the top drum portion when the drum is rotated, and wherein an endof said second portion of said drive string is connected to a springattached to a second of said terminal blocks. Rotation of the drum in afirst direction causes the pair of spaced apart terminal blocks to movetogether.

Robot Arm Sub-System

A robotic arm assembly, in a fiber optic cross-connect in which a robotselectively transports fiber optic connectors between distinctpositions. The robotic arm assembly includes an upper stage and a lowersection slidable in said upper stage; and a mounting mechanism throughwhich the upper stage is movable in a vertical direction, where themounting mechanism includes a plurality of spring-loaded lubricationmechanisms; and a plurality of rollers, including hardened and groundcrowned rollers. The spring-loaded lubrication mechanisms include alubrication element; and a spring positioned in a hole in thelubrication element. The lubrication element may be an oil-impregnatedplastic element. The upper stage may be case-hardened, non-magneticstainless steel.

Cleaning Cartridge Sub-System

A device for cleaning an end of a fiber optic cable, the devicecomprising: a drive mechanism; a pressure sensor; a source spool offabric; a take-up spool operatively connected to the drive mechanism;and a plurality of guide rollers to guide the fabric past the pressuresensor to the take-up spool, wherein contact of a fiber connector tip onthe pressure sensor causes the drive mechanism, after a predetermineddelay, to rotate the take-up spool and advance a predetermined amount ofthe fabric from the source spool to the take-up spool.

Fiber Optic Tensioning Reel Sub-System

A tensioning spool apparatus for storage of optical fiber exhibitingreduced variation of tension during a retraction cycle versus anextension cycle of fiber over a predefined range of spool rotationcycles, the optical fiber dynamically extended under tension from thespool. A first spiral element includes a linear spring, a length ofoptical fiber characterized by an insertion loss dependent on its bendradius along a length of element, and an outer sheath with the linearspring and the fiber therein. The first spiral element is sufficientlyflexible to reduce adjacent turn interaction force and binding underbending, while being at the same time sufficiently stiff to preventbuckling of spiral during unwinding and ensure that a bend radius of theoptical fiber is at all locations and for all configurations greaterthan a minimum bend radius specified for the optical fiber. A secondspiral element includes a flat coiled metallic spring. The second spiralelement produces greater average torque relative to an average torqueproduced by the first spiral element. A flat, non-rotating substrate isin a first plane, the first spiral element in a second plane, the secondspiral element in a third plane, and the first, second and third planesare parallel, and the second plane lies between the first and thirdplanes. The average torque transferred to the tensioning spool to driverotation is equal to a sum of the average torque of the first and secondspiral elements, the variation of said tension resulting primarily fromfriction between adjacent turns of the first spiral element, an outersurface of the sheath having a low coefficient of friction with itselfto minimize the variation in tension.

Fiber Optic Tensioning Pulley Sub-System

A fiber optic cable tray system with a three dimension array of pulleysis disclosed, comprised of a central, stacked linear array of flexible,low friction through guides attached to substrate, and a multiplicity ofthe length buffers arrayed on the substrate, wherein the length bufferseach include a spring-loaded moving sled with a multiplicity of freelyrotating pulleys on a moving common shaft, and a spaced-apart fixedcommon shaft with an equal multiplicity of freely rotating pulleysthereon, wherein the fiber optic cable wraps in a repeated circuitaround opposing sets of pulleys on the moving shaft and on the fixedshaft and is routed through one of the low friction through guides to afiber optic connector at the distal fiber end. Multiple identical trayscan be stacked on top of one another within a common housing, to producemodules with a number of cables in multiples of 12.

1-59. (canceled)
 60. A tensioning spool apparatus for storage of opticalfiber exhibiting reduced variation of tension during a retraction cycleversus an extension cycle of fiber over a predefined range of spoolrotation cycles, the optical fiber dynamically extended under tensionfrom the spool, the apparatus comprising: (A) a first spiral elementcomprising a linear spring, a length of optical fiber characterized byan insertion loss dependent on its bend radius along a length ofelement, and an outer sheath with the linear spring and the fibertherein, wherein the first spiral element is sufficiently flexible toreduce adjacent turn interaction force and frictional binding underbending, while being at the same time sufficiently stiff to preventbuckling of spiral during unwinding and ensure that a bend radius of theoptical fiber is at all locations and for all configurations greaterthan a minimum bend radius specified for the optical fiber; (B) a secondspiral element comprising a flat coiled metallic spring, wherein thesecond spiral element produces greater average torque relative to anaverage torque produced by the first spiral element; and (C) a flat,non-rotating substrate in a first plane, wherein the first spiralelement in a second plane, the second spiral element in a third plane,and the first, second and third planes are parallel, and the secondplane lies between the first and third planes, and wherein the averagetorque transferred to the tensioning spool to drive rotation is equal toa sum of the average torque of the first and second spiral elements, thevariation of said tension resulting primarily from friction betweenadjacent turns of the first spiral element, an outer surface of thesheath having a low coefficient of friction with itself to minimize thevariation in tension.
 61. An apparatus in accordance with claim 60,wherein the tension varies between 10 gm-f and 80 gm-f
 62. An apparatusin accordance with claim 60, wherein the low coefficient of friction isnominally less than or equal to 0.25.
 63. An apparatus in accordancewith claim 60, wherein the minimum bend radius is approximately 5 mm 64.A tensioning reel system optical fiber comprised of two helical springs,comprising a first spring and a second spring, rotating about a commonaxis and producing an additive torque about a common axis, the firstspring fixed to a central mandrel and the second spring fixed to anouter ring, wherein the first spring produces greater torque than thesecond spring, the second spring is a multi-component assembly includingan optical fiber, a straight wire and an outer sheath, and the firstspring does not include an optical fiber.
 65. A tensioning reel systemin accordance with claim 64, wherein the helical springs rotate byidentical angles about a common axis as the tensioning reel rotates. 66.A tensioning reel system in accordance with claim 64, wherein thehelical springs both unwind or wind about a common axis as thetensioning reel rotates.
 67. A tensioning reel system in accordance withclaim 64, including a circular mandrel on which optical fiber can berepeatedly wound and unwound, wherein the helical springs both wind to asmaller average diameter as the optical fiber is extended from the reelsystem.
 68. A system comprising a plurality of reel assemblies mountedon a sheet metal tray, each of said plurality of reel assemblies being atensioning spool apparatus according to claim
 60. 69. The system ofclaim 68, wherein the plurality of reel assemblies comprises 12 to 24reel assemblies on said tray.
 70. A system of fiber optic cable lengthbuffers that tension fiber optic cables, each fiber optic cable withdistal and proximal ends and extendable from the length buffer, thesystem comprising: a central, stacked linear array of flexible, lowfriction through guides attached to a common substrate; and amultiplicity of the length buffers arrayed on the common substrate,wherein the length buffers each include a spring-loaded moving sled witha stacked multiplicity of freely rotating pulleys on a moving commonshaft, and a spaced-apart fixed common shaft with an equal multiplicityof freely rotating pulleys thereon, and wherein a fiber optic cablewraps in a repeated circuit around opposing sets of pulleys on themoving common shaft and on the fixed common shaft and said fiber opticcable is routed through one of the low friction through guides to afiber optic connector at a distal fiber end.
 71. The system of fiberoptic cable length buffers of claim 70, wherein a length of fiberextendable from the length buffers is approximately equal to a number ofcircuits multiplied by the maximum distance between the moving and fixedcommon shaft.
 72. The system of fiber optic cable length buffers ofclaim 70, wherein the spring-loaded moving sled is attached to a pair ofpower springs at one end and attached to the common substrate at theother end and extends in opposition from their fixed housing.
 73. Thesystem of fiber optic cable length buffers of claim 72, wherein anaverage tension of the fiber optic cable is equal to a total retractionforce of the pair of power springs divided by a number of circuits. 74.The system of fiber optic cable length buffers of claim 70, wherein thedistal fiber end is terminated in a connector that is connected and/ordisconnected by a robot system.
 75. The system of fiber optic cablelength buffers of claim 74, wherein the distal fiber end connector endface is cleanable by the robot system swiping the end face acrosscleaning fabric.
 76. The system of fiber optic cable length buffers ofclaim 70, wherein the outer diameter of the individual low-frictionthrough guides is less than or equal to 1.0 mm to enable a high densityof arrayed fiber optical cable length buffers.
 77. The system of fiberoptic cable length buffers of claim 70, wherein the outer diameter ofthe fiber optic cable is less than or equal to 0 5 mm to enable a highdensity of arrayed fiber optical cable length buffers.
 78. A method ofmaintaining tension of optical fiber cables extendable from arrayedspools, the method comprising: extending a first optical fiber cable ofthe optical fiber cables from the arrayed spools by robot actuator;sliding the first optical fiber cable through one of an array offlexible guides; rotating a roller attached to a rotary encoder togenerate encoder pulses; counting the encoder pulses; pulling theoptical fibers cable wrapped around spools in multiple circuits on asled traveling between two endpoints; rotating arrayed spools on thesled with different rotation speeds; translating a sled along a straightpath due to dynamic extension force of optical fiber cables wrappedaround spools of the sled; and pulling one or more springs attached atone end to the sled from their housing to impart a restoring force thatmaintains the tension.
 79. The method of claim 78 wherein the tension isin the range of 20 gm-f to 50 gm-f on average, and wherein the tensionincreases as a length of the first optical fiber cable extendedincreases.
 80. The method of claim 78, further comprising: comparing anumber of encoder pulses to a calculated extension length to verify thatthe first fiber optic cable is properly extended or retracted.
 81. Themethod of claim 78, further comprising: driving the robot actuator sothat the travel of the sled is a fraction of the travel of the robotactuator.
 82. A fiber optic cable length buffer device thatauto-tensions a moveable end of an optical fiber cable that isextendable from the length buffer and opposite a fixed end of theoptical fiber cable, wherein the length buffer comprises: aspring-loading translating sled with a multiplicity of freely rotatingpulleys about a common first shaft affixed to the translating sled; anda spaced-apart fixed common second shaft with an equal multiplicity offreely rotating pulleys thereon, wherein the fiber optic cable wraps ina repeated circuit around opposite pairs of pulleys on the common firstshaft and on the common second shaft, and the moveable end of fiberoptic cable is routed through a low friction through guide to a fiberoptic connector, the force produced by spring-loading on sled equal toan integer multiple of the tension force imparted on the moveable end ofthe optical fiber cable.
 83. The buffer device of claim 82, wherein aratio of a pully's outer diameter to the shaft's outer diameter is about10 to
 1. 84. The buffer device of claim 82, wherein a tension forceimparted on the moveable end of the optical fiber cable is in the rangeof 10 gm-f to 50 gm-f.
 85. The buffer device of claim 82, wherein theoptical fiber cable has a low friction, wear resistant protectivecovering with outer diameter of 0.25 to 0.5 mm
 86. The buffer device ofclaim 82, wherein the optical fiber cable is comprised of one or moreindividual optical fibers. 87-124. (canceled)